Did it on a 110g drilled tank with a black acrylic backgroung I hated. Split the tiles and broke up the pattern over a bulge in the plastic center plate.
I have one tank thats been setup for 20+ years without a complete tear down and cleaning so the 'gunk' that may find its way behind the slate does not concern me. I disabled the UG filter plate on the old tank when I went to an eheim canister (2 years ago) and had no strange issues occure. What little debris may find its way behind the slate will help feed the moss I'm starting along the seams anyway.