DIY Overland Trailer Build Part 2: Design

In my previous article on building a DIY overlanding trailer, I explained my rationale for building a trailer myself and how I decided what type of trailer I wanted to build.

Here I’ll talk about the process for designing an overland trailer — or at least the process I used. Like I said in my earlier post, I’m not a professional trailer builder nor am I an engineer, so do your own research and consult professionals when necessary.

Topics

• Research

• Building a Flexible Platform

• Downsides to My Approach

• Design Tools

• Tools and Skills

• Trailer Elements

You can also watch the video that corresponds with this article:

Research

The first thing I did was do a lot of research. I looked at other websites on overlanding, perused trailer manufacturers’ marketing materials and specification documents, and read through online forums where people had posted their build threads.

I also went to a couple of overlanding and off-roading expos to check out commercially manufactured trailers in person and talked with trailer owners I met on the trail about their trailers.

How much design work you do in advance depends a lot on the complexity of your project. If you want a simple cargo trailer to carry gear and supplies, you’ll have to account for far fewer design elements than if you’re planning a sleep-inside teardrop trailer with running water and a solar-charged battery-powered electrical system.

Erring on the side of simplicity made sense to me as a first-time trailer builder. Even with the fairly simple build I imagined, as the various elements of the trailer came into focus – wheels, suspension, frame, cargo box, tent rack, etc. – my brain overheated a few times, trying to plan how to mesh everything together.

Building a Flexible Platform

I reached a critical thinking limit when I started attempting to add water and electrical systems to my designs. There were just too many elements to consider and too much new material to learn. It felt like I would never get started actually building my overlanding trailer.

Facing despair, I opted for a progressive enhancement design philosophy—meaning I would design the bare minimum trailer for use in the backcountry and add other bells and whistles later.

The goal was to come up with something simple, functional, and flexible. I drive a Jeep Wrangler, which is sometimes referred to as a “platform,” as it can be modified in endless ways. I decided to adopt that mindset for my overland trailer.

Really, all I needed at first was a sturdy, off-road-capable box on wheels that could hold gear and supplies and pass DMV inspection so I could legally drive it on the road.

Once it was road-worthy, I could progressively add enhancements. My goal then was to design a basic trailer that I could take on trips and continue adding to over time. This broke down into these objectives:

1. Wheels, suspension, and base frame capable of off-road travel

2. Cargo box to carry gear, supplies, and an overland kitchen

3. A rack on top of the cargo box capable of supporting a roof-top tent and the weight of three people

I’ll outline how I tackled each of these components, both the design and build, in subsequent posts. But first, I want to talk a bit more about the elements I wanted to include in the trailer, my design tools, and some of the downsides of my approach.

Downsides to My Approach

Leaving some design elements for later in the project has some drawbacks. The main problem is that the base trailer may not be optimized for the components I add later in the process.

Eventually, I want to add cargo sliders, a water tank, lights, a portable refrigerator, and other bells and whistles. Ideally, these things would be planned out in advance — and I have given them SOME thought. But I left the details to solve at a later date, which led to some unforeseen complications, which you’ll read about in future posts.

All that said, I still think my approach was the way to go for a first-time builder. If you try to account for every design detail in advance, there’s a good chance you’ll never get to building.

Design Tools

My first instinct was to design the overland trailer in SketchUp, a popular CAD-type tool. I soon realized that I needed a lot more flexibility to sketch things out and make significant changes of direction.

To that end, I decided to use plain old graph paper, pencils, and various hand-held rulers, protractors, and compasses. I went old school.

If I had had a firmer idea of what I wanted to build and better CAD skills, Sketch Up or another design software might have been the way to go. But I’d still probably sketch out early concepts on paper.

Where a CAD drawing would be particularly helpful is if you need to have parts fabricated by a shop. Giving them a precise drawing from a standard design program could make it easier/cheaper.

That said, based on my research, I was pretty sure I could produce a working design using pencils and paper.

Tools and Skills

I’ll get into more detail about some of the tools and techniques I used to build my overland trailer in the next article. But it’s worth pausing here to consider how those capabilities play a role in your design.

If you don’t know how to weld or would rather avoid a lot of welding, you’ll most likely want to start from a pre-made frame onto which you can bolt the suspension and cargo/sleeping box.

You could either build on an existing trailer, such as a military surplus trailer, something like the Harbor Freight trailer mentioned in the previous post, or a purpose-built off-road trailer frame like those made by Dinoot.

The more custom your trailer, the more tools you’ll need. If you buy a prefabricated frame, suspension and box, you will likely be able to bolt most things together. Keep this in mind as you start designing.

Trailer Elements

When you are designing the trailer, it’s helpful or maybe even necessary to break the design into major functional aspects of the trailer. Since I was building a cargo trailer capable of carrying a rooftop tent, my design needed to incorporate the following elements:

• Frame

• Trailer hitch and safety chains

• Suspension

• Wheels and fenders

• Cargo box

• Cladding

• Stabilizer jack

• Tail lights and wiring

• Cargo rack for tent

• Paint

In addition to these essential components, I also kept in mind some other elements that I wanted to potentially add on later. These included:

• Overland kitchen slider

• Water storage

• Gear storage and tie-downs

• Racks for mounting awnings

If I had decided to build a more complex trailer, such as a teardrop trailer with a bed inside, I would have had other essential components that needed to be accounted for. These might include the sleeping platform, ventilation, internal lighting, and other components required for sleeping inside the trailer.

Even more complex designs for large camper trailers might include plumbing for showers and toilets, electronic outlets, and full RV-style kitchens. This being my first rodeo, I followed the mantra of keep it simple, stupid.

In the next installment in this series, I’ll cover designing and building the trailer’s frame and installing the suspension and tires.

All Overland Trailer Build Articles

• Step 1: Choosing a Trailer Style

• Step 2: Design Process

• Step 3: Frame Design and Fabrication

• Step 4: Cargo Box, Doors, and Fenders

• Step 5: Cladding, Trim, and Painting

• Step 6: Wiring Harness and Tail Lights