poly tank questions

[Jwill41]

I installed the poly tank from GMCPaul underneath my stepside last year. I have the filler clamped under the fender but want to mount it in the floor.
1st problem: I bought a marine filler but it is bigger than the neck on the tank. I had to split the outer layer of the hose to get it over the marine filler(not good). I could not find one the same size as the tank.

2nd problem: I have seen the post about heating and bending the neck straight up. It looks to me like it would have to "stretch" so far that it might tear. I am afraid to try this.

3rd problem: The tank is almost touching the wood in the floor. This leaves no room to attach the hose and marine filler as it is now. This would be even worse if bent straight up. Do I need to lower the tank with spacers or something? Don't really want it to hang any lower.

4th problem: I am getting water in the tank. I drained it yesterday and there was an extreme amount of water inside. It appears that the sending unit does not seal very well. What kind of sealer could I put around it that gas wound not desolve.

Please help someone. I am getting tired of reaching under the fender to fill this thing. I plan on starting to drive it daily if I can overcome a couple of these small problems. Thanks in advance.