I wanted to close this out with what I found out when I got in the belly of the camper. First the floor had been replaced at one point below the water heater/water hookup/pump area. The dealership that did the work didn't do that great of a job when it came down to finishing the work. The pump was only screwed down to the floor on 1 side, the other side was actually off the floor. They also screwed it down right under the 2 water lines that ran to the back of the camper. So the pump was vibrating them. I made my own flex hose kit and moved the pump away from the pipes. A lot quieter now but the test will be in a couple of weeks how it performs when we stay at a national park with only electric. Also one of the screws in the head of the pump vibrated out and is stripped so eventually we will need a new pump anyway.
The fridge fan has actually gotten somewhat quieter. I couldn't hear it as much this last weekend at the lake. The sound of it is still noticeable but not as bad. I will wait and see what happens after we store it this winter.
Haven't figured anything out on the water heater, it does have brass check valves with the plastic check valve inside. Not sure if I can replumb the camper to eliminate the need for them. I figure it really only needs the one side of them for when you bypass the water heater. But we never put antifreeze in, we only blow air through our campers.
Didn't do any work on the fuel station.
Longer Fuel Hose for Toyhauler
But I did find this forum where someone else did exactly what I would like to do so we can extend our hose.