Should fresh water tank be patched or replaced?

If it shows a patch from the factory, a new tank would be the only logical repair. Of course if the dealer could 'weld' repair it properly, then that would probably work as well. Just putting some sort of glue on a plastic tank just wont work.

As far as any new tank - it makes me cringe to think of the ham handed RV lot mechanics I've come across in 40 years who could be working on my new $$$ 5er