/diy/ - Do It Yourself

>offroad capable
you probably got a few options
>slide in camper - ready to go, just get the truck you want and find a camper in your price range cheap / free ones will need some work.
will be tippy on trails
>just get a topper and build one inside the truck bed
low skill required but tight / small space
wont affect mileage or off road capability
>buy an old cube or cube truck off craigslist and the 4x4 you want, replace the truck bed with the cube and scrap the other truck
good platform to start with, more space, might affect off road capability
>DIY
hope you are good with power tools and at least have some experience with fiberglass (glassover plywood for weatherproofing)
will likely be the heaviest option because unless you know what you are doing you should probably overbuild rather than have your camper fall off your truck on the highway or trail