Several options for caring for your new batteries.
1. Your suggestion, pull them out and put them in home intensive care. Not a viable option for the stated reasons.
2. Disconnect them and go down to the boat periodically and top them off with whatever charger
you have on the boat. Cheapest option (if the boat isn't too far from home) and added benefit you get to go hang out on the boat every few weeks.
3. Buy a new charger, ideally a smart, multi-stage charger with a maintenance
or trickle mode and a circuit to prevent over charging
4. Make sure the batteries are well secured in the boat, sail boat to FL. Once there recharge the batteries from the alternator
while running the engine
from the dock
to the channel before hoisting sails
. Repeat as necessary.