Other items are specific to each vehicle such as water clean out, Tire/window shades, etc.Quick non Parking list:Wheel/tire covers; Vehicle cover.Remove and store your tires.Store with a full fuel tank to prevent condensationAdd fuel stabilizersPlace RV completely off the ground to prevent flat spots on your tires, if left for a long time.Cover your HVAC, skylights, vents and windows to prevent exposure to sun and breakdown.Boats leave your plug out, whether covered or not.

You could also look at laying a floating floor over the existing carpet (depends on what it is) and then take it with you when you leave.The risk to the owner is the tenant leaves behind a substandard floor and you have to pay for new flooring.Try professionally cleaning the carpet (or rent a professional machine).

Make the Seller get rid of them so it is vacant and clean before you become the owner.

Let the contractor have the place to himself, get it done, cleaned up and then rent it.

We also look at the building, landscape, painting, general clean up.

I live in Arizona, and Ive replaced couple of AC's in my rentals and my home, and Ive never had to clean nothing in my AC or related to AC with bleach not vinegar.

House needs some painting, carpet, yard clean up, etc.

Figure out what you could buy it for that makes sense for both of you, rent it back to him, and just make this a clean sale.

I'd rule out the STR in Van due to 1) price/cashflow 2) unfavorable policies 3) Like you said, its big capital locked up for a small property with limited usage 4) STR is either a TON of upkeep(cleaning, marketing, etc) or a TON of expense related to prop mgmt in an already tight cashflow scenario.  

Much easier to clean.