In my eleven years of full timing experience I have found that most don't allow maintenance but some do.
One where we stayed in NH let me install a fan clutch in my last motor home -in fact he came down and gave me a hand with a bolt that was very hard to reach with the wrenches I had.
He was also okay with me installing brake pads on my Honda.
We were lucky enough to have an RV site available at my wife's sisters commercial peach orchard in CO. That is where I did things like installing laminate flooring in my present coach.