A few of the folks here on the forum have built the box off of the truck and then installed it later. Myself and some of the others built it right on the truck.
I don't see a problem building on the ground when you have the truck right there for measurements, but I would worry about trying to do it without the truck there. Some things are pretty standard, like the frame rail width and spacing, but other things vary like the height of the cab if you are thinking about an overhead bunk. Or the wheelbase of the truck you find may affect how you decide to build, unless you are planning on having the truck stretched or shortened to match the box you build.
Just thinking out loud. Good luck with the project.
|