Some CGs do & some CGs don't let you do anything.
I have not come across a CG that has not let me do a minor repair. Just removed the remains of a TV antenna off the roof today at a KOA. Nothing but waves from the people zooming around in the golf carts.
As long as you are reasonable most don't seem to mind. Changing oil, engine tune ups, noisey jobs are not reasonable.
Boat: 32' 1996 Albin 32+2, single Cummins 315hp
40+ night per year overnighter
2007 Alpenlite 34RLR
2006 Chevy 3500 LT, CC,LB 6.6L Diesel
Ham Radio: VP9KL, IRLP node 7995