Thanks for the support.
Yes the problem is probably due to improper build. Discovered after extended stays at sites without sewer connections. Now I carry 2-5 Gal jugs & watch the handle. As soon as I seen any sign of the tank sagging I drain the tank.
Dealer opened the bottom examined the tanks (4). All mounted identically, method of waste valve mounting is different on this tank. Dealer took pictures of all 4 tanks and is sending them to me. When I get the pictures I will send them & pictures of the bent handle with description of the problem to manufacturer and see what happens. Hopefully to the satisfaction of both of us.