While I have to believe that times have changed, and FastB may want to weigh in here...
I lived hassle free in two different marinas in Sausalito for 6 years in the last years of the 90's. Sneak-Aboard
Zero problems at all. I was super nice to the harbormaster and helped solve/point out any concerns that would help the harbormaster in ways that simply made his job easier. (not being a busy-body)
Storms I would walk the dock and tie up loose boats and furlers. (this seemed to be a big help)
Boat was kept super tidy and was used frequently. (again important as that the squatters seemed to have more trouble)
I made blackout curtains, but I suspect that it made little difference... I showered aboard, but did use the coin operated washing machines.
Vehicles moved regularly, and never sat in one spot for more than a week at most. (and kept washed)
Always always pay on time.
There was more I'm sure, but you get the point.
Awesome time and experience. I loved taking the ferries to and from the city for work.
I say go for it, and if you get booted, go politely to a different marina or put it on a truck and have it towed somewhere else. Hauling is not hard or expensive in the grand scheme of things.