Ok the doors are all power, can't seem to find the seatbelts but I know I've got them somewhere. I do at least have the front seats :)
I'm headed out of town shortly but will be back Tuesday so I can look some more.
Let me look tomorrow but I know I have 2 front seats out of a 91 and I do have doors just can't remember if they're power or manual. May still have the rear seatbelts too.
I have an extremely built 44 that's about 90% bolt in to an xj that I may be tossing up for sale shortly. Pm me if your interested. It's the same width as your stock axles too so you can remain street legal if you wanted.
I dont know of any rental agency that would rent a suitable 4x4 so I'm no help there.
What I would do is get with a group doing it and rent a seat. You can see more as a passenger than driver in my opinion. I have a friend from Austria that comes once every few yrs and rents a friends rig from...