Just a comment on the "where to put the spare issue". At the place I used to work, we did A LOT of off-roading in very remote areas, utilizing Jeep Cherokee's, Toyota Pick-ups, a big Dodge diesel pick-up, an Isuszu Trooper and an Isuzu Rodeo. The Rodeo, while having plenty of power and pretty good gearing had a spare tire that, due to the way it was mounted under the vehicle, actually was lower than the rear pumpkin. Well, myself and a couple of the other guys had disagreed with the idea of purchasing this vehicle, due to this spare-tire issue. However, in 2-plus years of heavy use, and multiple hard hits, the spare was still there when I left. Sure, the rim is beat up and the tire has some scuff marks, but it stayed put. I can recall numerous times, after having rock-crawled my way up a mountain or washed-out pipeline, dragging the rear-end all the way convinced that I had destroyed the spare, getting out at my destination and finding it still there. The spare on the Xterra is much higher than that on a Rodeo, so I wouldn't worry about moving it. The only vehicles that, in my opinion, have any right to carry a spare on the roof is a Jeep Cherokee or some other similar vehicle that locates the spare inside the rear cargo area. Then, if you carry a lot of stuff, the roof may be the only option (save a new bumper/tire carrier, which is just something that is in the way)

Just my $0.02 worth