Nothing against Jeeps, Toyota, etc. Just throwing ideas out there with what I'm most familiar with. Cheap rovers (RRC, D1, D2) are all over the place and ready to be hacked up. The bodies are marine grade aluminum, I'd say 60-100 thou depending on area. Frames are very heavy. There's a reason they weigh and tow more than Jeeps, and it's definitely not all the aluminum. I have no problem finding cheap parts. Just a matter of using good vendors. Any issues are well known and all have fixes.
But if not that, then why not an older Unlimited with upgraded HD drivetrain?
I mentioned it a few posts back, but I agree that this concept could be built in a lot of other chassis.
All the 90-110 rover stuff I have seen has been pretty much trash. The frames, though boxed, where pretty dang thin material. The same goes for the bodies. That is just my hands on observation.
The range rover and defender stuff just isn't my thing. I would end up hacking and chopping those up so far to get the vehicle as low as I want on the larger tires I want to run.
On the unlimited. It is an option, I have talked about it before. They aren't really giving those things away just yet. I'm not sure if your talking about a JKU or an LJ. Decent units in my area are going for $12-15K. On the LJ really wasn't a ton of them made in the short production run and they are pretty desired as vehicles. For what I want in the end I would end up pretty much gutting the vehicle and having to redo a lot of it. I like fabbing as much as the next guy, probably a little more, but making heavy duty modifications to modern sheetmetal sucks. Most of that stuff is around 18-22 gauge and welding in things like a larger tunnel or larger rear wheel tubs just flat sucks. You might be able to sell off a lot of the stock parts, but you also have to remove them, package them, sell them, and ship them to recover any of the money. Also, in some ways registering a scratch built vehicle might be easier than trying to register just an OEM tub that already has a VIN tag....especially if the tag is salvaged or you don't have the title.
On a lot of levels I think having a nice clean canvas will be VERY nice. I will still have to make a few mods to the Aqualu tub but it will be all on fresh clean thick metal without undercoating, paint, primer, e-coating, etc. In the end I will probably end up with a vehicle that is more spartan than a 2005+ OEM vehicle but I am ok with that. I'm coming off my Willys build and that thing is basically a go-cart.
For how in depth this build will be I don't see using a 'blank' aftermarket tub as a bad being a bad thing....same goes for the frame. If your going to build something this crazy why NOT start with just the bare minimum walls on the box. I have also very seriously considered building a vehicle completely from scratch. For me....that is like pandora's box as far as choices. By using an aluminum LJ tub I have a few limitations to work around but they seem to be just enough to keep me grounded and making progress with the design.