I was not pleased with the padding for the main tank. It could still move from side to side (not fwd & aft) so I added more padding to the double rib. Its secure now! I cut a strip from the flooring material I had laying around. Its oil resistant and pretty firm. I riveted it to the rib a few placed and now the tank is secure! I want to keep the tank as close to the root rib as possible and my drain hole is already cut so keeping it in the same location is critical.