Have you tried to weld it...with a plastic welding gun? I'm talking about the tank. Harbor Freight Plastic Welder
. I've never used one, but it seems to me there was a discussion at one time...maybe pre-hack
The dump valve assembly is just a standard, off-the-shelf at an RV supply store. Basically, it's just glued in, using something like JB-Weld
. If you could cut that off and replace it, after fixing the tank...you'll be money ahead. I see from the 2005 Scamp parts list, they want $140, for a gray water tank and fittings.
someone also has installed a stainless steel gray water tank.....