In the tropics a wood boat must have bottom paint to prevent worms from boring into the wood. If your boat is fiberglass
and you are scraping it constantly there is always the chance of being too aggressive and scarring the gel coat or wearing it away. This lets water intrude. Even for fiberglass
it is not good and can lead to water migration and blisters
I would not put a boat in saltwater without bottom paint.
I don't know how many times you've aggressively cleaned the bottom of a 35ft hull
but 4 times a year in my opinion is too many times. Takes a lot of air and effort.
Good luck in whatever way you choose but I'll bet you'll be buying
some good bottom paint after the first year.