I had the '93 Sailfish for about 12 years (she was a year old when I bought her), before Brian bought her. During the time she was mine, I took the deck plates up a couple times a season, and rinsed, and wiped the top of the fuel tank. Left the deck plates off for a day, to dry out below. I also left the deck plates off during winter layup while she wa shrin-wrapped. Inspect, and clean or replace the O-rings from time to time, and lube them with plumbers grease (used for lubricating faucet valves.
When Brian had the boat surveyed, the surveyor made a comment to the effect that the tanks looked like new. In fact, the whole boat surveyed so well, that the only things he could find wrong, (remember this was a pre-purchase surveyor hired by the buyer), was the forward blge-pump float switch was stuck, and there was a spider in the anchor locker!!!
I think that's a pretty good survey for a boat over 13 years old.