I assume you reviewed this thread you started last year? How Expensive is the Virgin Islands to Live on Board ?
I'm not a live aboard but I do always try to provide information pertaining to St Thomas. I'm friends with dozens of live aboards. With that in mind-
The least expensive marinas that I can think of for your Islander 36 would be about $16/ft/month plus electricity, plus water. Most of the folks I know that live on the dock use some form of air conditioning which swings the electric bill up another $100+/month. I would think an average dockage of $700/month would be possible. Most of the people that I know that life in the less expensive marinas have cars so they can get to work. That would need to be added into your budget.
The other option is to drop the hook in the harbor downtown, Red Hook out east or Hassel Island west of the harbor. That is FREE.
I understand you've read about the regulations.... Perhaps if you thought of them more like suggestions rather than regulations, it would be to your benefit.
I think of regulations that have not been enforced in the 8 years that I've lived here more as suggestions. When the head of enforcement plead guilty a couple of days ago to using enforcement vessels to move cocaine and money, that sort of explained where the priorities of the department were! People on the hook either have a water maker, jerry jug water via dinghy or just motor into the nearest marina to top off tanks.
If I were intending to work while here, I would probably aim for the ease of living in Compass Pt or Independent marinas. If I had no intention of working, I would anchor wherever I liked and then make arrangements to pull the boat out of the water and store it on the hard someplace. I would NOT leave a boat unattended during hurricane season on a mooring or anchored. The two marinas I listed are the most secure for hurricane protection but do have long waiting lists because they are so safe. The two marinas I suggested are towards the east end and are kind of away from stuff. There is a very good grocery store across the road and a couple of small bar/restaurants within a short walk. Anything else will require a safari ride (dollar taxi) or bumming a ride.
If you tell me what your intentions are, I could try and provide more specific info.