That tank is way nice and has way too much potential to give up without putting a good effort into it. I'd say goodbye to that whole filter mess that's in there now, go with the complete re-seal (not disassembly). That's a lot of seams to re-do, and they've all got to be done in one sitting, no taking a break halfway and then continuing tomorrow allowed. So, have all I's dotted and T's crossed, and make sure everything is gathered and ready before you start.
That tape idea suggested by
Gpdriftwood
sounds fascinating. Does that require using some silicone or other sealant where tape overlaps tape in the corners, to make sure there isn't some tiny crevice or channel between the strips?
I hope you try the tape idea...at least partially because I am anxious to follow along and see how it goes.

Good luck!