Been there, done that.
I used two cut lengths of 1x2 lumber to wedge in place against the tank wall, which pushed the tank in about 3/4 inch, enough space needed to reinstall the valve without twisting the seals. I also put some petroleum jelly on the seals to hold tthem in place while maneuvering the valve into its seat.
Job was a pain but next time will be much easier.
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