Been there done that with northern strain male bluegills in an almost 3/4 acre pond and still doing it. Works quite well. Bill Cody, Bruce Condello, and others were my mentor on this technique.
I routinely harvest males over 1 lb. with my personal best 1 lb. 8 1/2 oz. The fish are almost as tall as they are long as a 9.5 inch bluegill is already a pound. The 1 lb. 8 1/2 oz. fish was only 10.5 inches. Keep in mind I measure on a board so if measured with a tape they would measure 1/2 inch longer.
Myself, in a pond that small, I would not add fatheads, but pellet feed as to make sure all your fish biomass is in the bluegills.
One thing to make sure of, if you want them to be all males: If there is any doubt whatsoever it's a male -- keep it out! Typically from my experience you can't be 100 percent sure until spawning season, and the fish is at least 8 inches in length.
Cody puts fish in cages until he can sex them. Mine are hatched in a separate 1/10th acre pond and seined out in late summer and brought in side to recirculating tanks for the winter and for about a year. I can get them to 8 inches in less than a year this way.
