I would try to feed the carp until they are satisfied enough to wonder off. Then, see if any other fish types come to the feed. I realize this is not a long term plan, but it would tell you if the gills are there in the waiting.
Another option would be to feed the carp in their usual area, then hand feed in a different spot to try to attract the gills while the carp are busy elsewhere.
If your carp are dense enough at feed time...try a throw net to cull them out.
