I'm using stitch and glue to fabricate the black tank which will sit above the subfloor in the rear curbside bath. It should be a good technique for the tank, especially as it's easy to shape it to fit the Airstream curve. Materials will be a 1/4" plywood core, epoxy, filler and fiberglass cloth. The tank will extend through the bathroom bulkhead and under the bed so the little cleanout sprayer fitting can be hidden.
Yesterday I got the plywood pieces cut out and glued the first layer of 1/8" Baltic birch into a rabbet cut into the 1/4" plywood. The birch will let me make the curve on the sides of the tank. Today the bottom and sides were wired together to hold them in place temporarily for the epoxy.
We've got light snow and cold here for the next few days, so I may not get too far with this until it warms up a bit. The trailer heater warms it up just fine, but I can't keep it on unless we're there, so it really gets cold soaked. It has to be warm for Pam, so we went to the trailer, turned on the heat, and then ran errands for awhile to let it get warm. Pam is quite frail now and isn’t walking well, so it’s getting much harder to get out with her. Worth it, though, as she thought those snow flakes falling today were pretty cool.