Here's what you're looking at
Frank, I have an '87 and have removed the locker floor (okay, basically dismantled the entire locker including 2 bulkheads) to deal with leaking cockpit drain, rusted hot water heater, and rotted locker floor. The fuel tank is metal with no access plate that I can see to reach a hand in. To remove it you remove the large forward floor piece (mine wasn't even screwed in, though the screw holes were there), pull the floor piece up and angle it out of the locker, and you are looking down at the tank. The hoses from the water heater make removing it a little tricky, but I don't think you have to remove the aft floor piece that the water heater stands on. The fuel lines are on the port forward corner of the tank. The tank is not strapped or screwed down and had been held in place by the wooden support piece from the locker floor panel. Once you undo the fuel lines you should be able to lift it up and out, but you should siphon the fuel out first or the weight will be a problem. All in all, I would not attempt any of this if you aren't absolutely sure you have a tank problem...