I'll look at putting a valve in the line. I never thought of that but it would solve one part of the problem.
There are 2 seals leaking. When I flush the toilet, water comes out a seal at the top of the flush valve. I can get at it but need some way of getting it to seal better. It's not too big of a problem. The other seal I can't get at. Some times, the toilet keeps running. Last time we were out, we didn't know the toilet was still running. Luckily, we noticed the water rising in the bottom of the shower and turned the water off. The tank was over full. I had to drive very slow to the dumping station.