Millis... you did not mention the year of your 31. I would like to know how your project comes out. I have a 87 Hunter 31 and the fuel tank is hard plastic. I have also thought of installing a fuel guage, but haven't decided on how to do this. The tank is square in shape and the top has a little age sag in it, which I think will cause a leak problem if a hole is cut in the top where you would put the sending unit.
Benny, I like the sound of your system. Not really interested in installing something that will cause me headaches down the line. If you guys knew how I read the fuel level now, I may be laughed off this web site............