Interesting development recently that I will share.
While traveling some sort of road debris kicked up from a tire and dislodged the threaded manual drain for the fresh water tank. This occurrence created a small leak located where the drain line connects with the tank. This small leak ran along the side and then to the bottom of the tank. The water then started getting the thin piece of plywood, used for support, wet and soggy. The plywood lost it's strength and the tank began to sag and drip water to the ground.
It was at this point that I noticed the problem.
I will now reinforce the tank with thicker plywood and will hope to use the existing metal straps again. After pulling back the under liner, all sorts of construction practices emerged. I will post updates as my slow construction project continues.
I didn't have the same issue but did replace the plywood and I added two more braces under the tank and liner. I agree, the support used to be pretty weak. A lot of people have done this same mod. While the tank is exposed, you might check the fill and vent lines. Some have had these areas leak.
All fixed. I replaced the 3/8"plywood used to support the fresh water tank with 3/4" plywood. Was able to thread the drain line back into the tank with pipe goup and it didn't leak. Put the straps back up and screwed the liner back up and now am good to go.