Hey zidaro.....Not sure if you have heard of these guys....they build really nice prerunners here in San Diego. James knows his stuff....he might be able to answer some questions....http://sdtruckshop.com
Congrats.....I bought a '13 Tundra CM 4x4 recently with 20k on it. We've had it out in the desert a few times.....Does awesome bone stock.....But mods are in the works.
Be sure to keep us updated on your build.
I run General Grabber AT2s, load range E on our Sequoia 4x4. The Sequoia is not as heavy as a van....but still heavy. I've run this tire alllllllllllll over the SoCal desert, mountains and beaches of Baja. They've worked out great. I see you're in Nevada.....The AT2s work awesome in desert...