Overland Expo’s 2025 Ultimate Overland Build is here—a diesel Sierra HD and an OEV Back Country camper. This rig is designed to roam and is ready to auction for a good cause. Catch it at Overland Expo this summer!
Overland Expo has rolled out its 2025 Ultimate Overland Build, and this year’s rig pairs an OEV Back Country camper with a diesel-powered GMC Sierra 2500 HD AT4X AEV Edition. The goal? A well-balanced, long-range overlanding setup that will travel to all four Overland Expo events before being auctioned off to support land access and education initiatives.
Now in its fifth year, the Ultimate Build series takes a factory vehicle and shows what it can become with thoughtful upgrades. While the Sierra brings plenty to the table, this year’s build shifts the spotlight toward the truck camper—specifically, how the OEV Back Country transforms the whole package into a self-supported, all-season mobile basecamp.
The Camper: 2025 OEV Back Country
The OEV Back Country is a slide-in, pop-up camper designed for serious travel, not just weekend escapes. It’s built with R8 insulated composite panels and dual-pane windows to handle a wide range of temperatures.
The low-profile design keeps weight manageable and wind resistance down, while the pop-up roof gives you enough standing room to move around comfortably when you’re parked.
This particular camper is outfitted with a stainless-steel sink and integrated cooktop, fed by a 20-gallon freshwater tank and a Truma AquaGo on-demand water heater. A Truma Vario cabin heater keeps things warm on cold nights.
The electrical system includes a 220-watt Victron solar panel, a 270Ah Battle Born lithium battery, and a Xantrex Freedom X 2000 inverter—plenty for lights, devices, and refrigeration.
The Isotherm Cruise 65 fridge keeps food cold without drawing too much power, and a Lavabox portable propane campfire adds a touch of convenience where traditional campfires aren’t allowed.
Outside, an Alu-Cab 270-degree awning and shower cube expand the living space. Torklift Apex Anchors secure the camper to the bed, and smaller details like an Opinel knife set and Forrest Tool Co. axe/shovel combo round out the gear list.
The Truck: 2025 GMC Sierra HD AT4X AEV Edition
While the camper handles the living quarters, the truck underneath is no slouch. The 2025 GMC Sierra HD AT4X AEV Edition comes standard with off-road upgrades like Multimatic DSSV dampers, steel bumpers, and skid plates.
For this build, AEV added 37-inch BFGoodrich KO2 tires, a snorkel, a winch, and a load support system for the rear suspension. The powertrain—a 6.6L Duramax diesel paired with a 10-speed Allison transmission—offers the kind of range and torque overlanders typically look for when carrying this much weight.
Final outfitting was handled by Tiny Rig Co. in Southern California. They installed lighting systems using Vision X Explora and Optimus lights, wired everything through a Switch Pros SP9000 controller, and added a Midland MXT575 radio for communications. The truck’s cabin also features a Tackform TRAXX mount for devices and modular storage organizers from ONWRD Supply Co.
Other practical additions include a Viair portable air compressor, a Rig Ready Systems Jackout HD kit (with jack, impact gun, and repair tools), a Redzone Wireless internet system, and a Zoleo satellite communicator—offering connectivity and backup options for travel off the grid.
Experience It At Expo
The completed rig will be featured at all four Overland Expo events in 2025—Flagstaff in May, Redmond in June, Loveland in August, and Arrington in October—before going up for auction on Bring a Trailer. Proceeds from the auction will benefit the Overland Expo Foundation, which funds efforts to improve public land access, support community education, and promote responsible travel.
For more information about OEV, visit overlandex.com. Click here for a 2025 OEV truck camper brochure.
