Larry, I must say after viewing your work I am inspired... I think I am going to follow your lead. Wish me luck. The angle iron around the croplast, the clamps, and the rigid insulation inside makes it very tidy, and I can get inside if needed.
I've ordered a tank shutoff valve with remote cable... Almost bought the electric one, but decided KISS! That will solve the drain line outside of the heated space issue. I'll put 1" of rigid insulation (styrofoam). Because I have several sheets already, and seal the edges with spray foam. Then, a very neat coroplast application. I'll try to take some photos.
Joe