When I got my trailer I found a small soft spot under the water tank - no problem I thought... should be an easy fix. While it wasn't to hard it certainly took some time and money, so I thought I post it here.
It took some effort to take the water tank out, scamp
installs them before they put the benches in. I had to rip out 2 screws since I could not get to them (the wood was soft around them anyway) and disconnecting the fill and water line was really challenging.
The soft area in the inside was much bigger than what I had detected underneath, the whole surface under the tank needed some work.
First I had to dry the wood completely, this took over a week and I ran a small heater every night for a couple of hrs.
For stabilisation I injected git rot with a syringe every 2-3 inches. After that I applied another wood hardener (PC petrifier) to stabilize the surface. I applied some water tight epoxy to the outside to fill cracks in the fiber glass and filled the inside with miniwax wood filler. The area seems to be stable and very hard now, I think/hope it will hold up. Each step took me an evening.
Costs: 2x Git Rot (4oz) $38, PC Petrifier $9, water tight epoxy $19, 2x miniwax wood filler $33 = $99.
Ater all that, maybe I should have cut out the area and replace the wood, but I was afraid that there will be a cut on one side and I would have to connect it to the shell on the other.