You should even with limited movement, be able to do the simple stuff.
Water heater should be drained and flushed once a year to remove crud. If you have a Suburban wh, replace the anode rod. Blow out with compressed air (brush if you have one) the burner tube.
Furnace, blow out the burner tubes, a long flexible brush is also good to clean it out and remove and debris that gets in, including but not limited mud dobber nest.
Clean the inside return air filters to assure best air flow. Also check to make sure the seal between return/output is still in good shape to prevent cold air going right back up the return. VERY common problem.
Since you don’t seem to move often, invest in some tire covers to protect them from UV damage. Keep tires clean, and spray some 303 Protectant on them whenever not covered. BTW you might consider spraying any accessible plastic/rubber parts with 303 also to help ward off UV damage.
Try to find a local independent mobile RV tech to do the things you can’t do on the roof. You DO need to check the roof components annually to stop leaks ahead of time. And spray the plastic parts with the 303.
Included in many of the items above, remove the access doors, blow out the external parts to remove all debris, look for anything that might be corroding. #1 issue with many components is neglect.
