If you know any locals whose tank systems you trust, maybe "loan" your LR (a piece at a time) to someone local with large angels. Then after they're "cleaned" trade back for another sponge rock. This could turn into a symbiotic relationship
I've done this with grape caulerpa cover LR when someone's tang wasn't eating & it was no problem (since his tank system is way nicer than mine anyways
) His tang ate the macro & my LR got a good cleaning.
You'll have to weigh the risk vs benefit of this suggestion for yourself to see if the sponge really bothers you that much.
Just a thought.
Anthony