I got a LEGO Unimog for Christmas, once I'm done building and modding it, I want to try and build an H1.
I would love to have the unimog. It's a fantastic set! Just so you know, if the tire diameter is 3in, then you have the right height tires. If you go full studfull (think typical LEGO brick) then you are looking at a monster vehicle. If you go studless (exactly what the Unimog is), then it will be lighter. Check out two builders, Nico71 and Sariel for good tips on building trucks. Sariel is, uh, interesting considering he has tried his hand at Hummers. I personally don't like it, but hey, to each their own.
Give me about 15 mins and I will have some photos for you guys!