I'm not an owner but looked at them some years ago thinking something similar and seems like they could be a good platform for a small family or individual, all of them near me were took pricey though.
Make sure you will be fine with the rear swing door on the 460, it is a hurdle I would be able to overcome. Also, if you need to use the 3rd row and carry anything behind the seat that space is very small.
I swapped 100 series springs on the 04 Sequoia we had a while back and it did net some lift, we didn't have the air suspension so not sure what will be required. Maybe get some pics and post those for more feedback.
The normal thought on these is to buy the lowest mileage, best maintained one you can find for the money you want to spend. There will be some trade offs, I opted for 20-30k more miles because of the service history on mine and it was the color I wanted.
Cool trailer, had one like it in the past. For the one I had I swapped the fenders for some NOS military fenders that looked great, found them off of Steel Soldier website.