One has to just love the heat to live full time in AZ. I know when I was out there (79-82) it was a rough getting use to the heat in June,July, and Aug. the rest of the year was ok.
We have owned 2 5th wheels in the past and the roof and tires should be your biggest concern. I think the reason you seen the rigs up on jacks and such was to help firm things up and to take as much of the weight of the tires and axle bearings as possible. That heat might dry out the bearings and i would at the very least repack them before the next trip after setting for a year. As to the roof, we always had issues with the seals around vents and the AC units. Be sure to check these seals as much as possible. Both of our rigs had different roof, one was metal and the other had a rubber roof. The rubber roof had to be serviced every year, Cleaned and re-sealed. Something to think about for sure.
I hope i was of some help to you and good luck with the future full time thing, were getting ready to do the same in a couple of years.
Doug & Darlene Morgan RVM96 & Abby Gabby(pooch)
04 Dolphin 6375 LX W-24 Chassis #434136
"The Journey is our Destination"Hickory,NC