I have 2 peppermint shrimp in my tank and they don't eat any aiptasia. I've been told they only eat the very small aiptasia, and not bigger ones. As far as the copperband, let me know if it works for you. I have a pond that is temporarily housing just a puffer, and the aiptasia are going nuts in there. I was trying to figure out how to conquer that problem, and a copperband would be a cool fish to stick in there. I'm a bit concerned about the worms in the sand bed, though, will it decimate the population? How about the racoon, same thing?
By the way, if the rock doesn't have much other life on it, you might want to just try sprinkling kalk on it and then rinsing it off. I don't think the kalk would kill the coralline, but it will kill the aiptasia.