Sounds like you could get a nice RV. Pull the steepest hills you can find in Tucson and if there is a gen run it with full loads. While Tucson is low humidity moisture in the diesel fuel is possible due to condensation. Consider an additive.
The golden diesel rule is use higher volume stations and not small ones with limited turnover. AZ truck lanes have additional truck tax which doesn't apply to RVs. So if you use them be sure to tell them before the pump is started. And check the truck fuel fill size as truck nozzles are larger than gasoline.