TyW -- Based on what you have said, I think the largemouth bass-bluegill combination might work well for you. If productivity is reasonable (as you expect), you should be able to produce 8-9 inch (0.5-0.75 pound) bluegills with a crowded largemouth bass population. Largemouths can control bluegill reproduction to at least 30% surface area coverage of submergent aquatic plants, and some biologists would even argue up to 50% coverage. I'm not sure if that remains true with Eurasian watermilfoil, because I've never worked around that plant, but it should be coverage that is the key even with milfoil.
It sounds like largemouth bass and bluegill may be your best option, and certainly you would expect those two species to self-perpetuate without further stockings.
Dave
