Given your situation...I would absolutely remove the water filter permanently and go with an outside one though. Given all the horror stories in threads here about the FR water filters, many of us have removed them. Your situation is even more pressing, because if that filter housing lets go, by the time you gather your tools and remove the fireplace and access it you will have a lot of water damage....Even if you just get a slow drip, you will never notice it till you have soft or rotten floor issues....if I were in your boots, that would be my #1 priority...just check out threads in here about those filters...just another stupid design by FR, that someone should be fired over.
2011 GMC Sierra 2500HD
2014 Rockwood 8289WS, Diamond Pkg.