So we have a 1991 Chevy Bluebird. We have almost 7" space and we want to use the luggage compartments for our fresh water and gray water tanks (compostable toilet). Don't worry, we have already figured out the freezing with insulation, heat pads and floor access in the bus; completely sealing off the compartments (with the exception of the drain which will double as an outside tap). There seems to be NO THREADS on this at all!!
My question is not if its possible but rather what would you use to reinforce the compartments holding almost 600lbs of water. I was thinking galvanized cable vertically and horizontally, drill a small hole in the floor, feed it through a steel rope clip on the inside.
Any ideas would be helpful. Trying to avoid welding tools.