Hi- I have struggled with the same problem. When I bought the boat, there was a 6 gallon tank in the area under the cockpit. I used it the first 2 months I sailed the boat and it often smelled of gas in the cabin. So I bought a 3 gallon tank (Tempest) that almost fits into the transom well. WHat looks like a better fix is the U shaped tank that you can buy called a
Dinghy-Mate but i haven't tried it yet to see if it would really fit. What I also have considered is doing the mod that was done on later models where the tank is in a separate locker that is under the cockpit
seats. I have also considered widening the transom well by cutting the front out and sealing the 2 inch space between the front wall of the transom and the rear of the cockpit. This would allow the 3 gallon tank to sit in the tansom well comfortably. I would be interested in knowing how you deal with the problem. I don't think having the tank under the cockpit is a good alternative because of the fire danger. I go camping with my son on the boat and I don't wnat to take the chance.
Mike