I have a seven acre pond I built ten year ago. Before it filled with water I built structures using large sand stonerocks at varying depths down to twenty-five feet. Much the same way you would design a home aquarium.
Prepared the soil to the correct PH, dumped 250 ton of sand creating a small beach for the gals. Landscaped a path around the perimeter for on-shore fishing and two feeding stations where you can enjoy the fish feeding. Stocked with Bluegill, Shellcracker, Largemouth, Cats and Grass Carp. My most wonderful achievment is putting a smile on a child and watching their reaction while fishin.
Pond size really doesn't matter. If you take care of the largest bluegill, they will protect the smaller bluegill which are destined to become the largest bluegill you will grow. When a bluegill begins to spawn, most of their energy goes into egg and sperm production...and nesting. When they are focused on reproducing, they stop growing. When they stop growing, they lose the potential for largest sizes. When your preserve the biggest bluegill, they will "hog" the nests and keep the smaller males off the nest, "allowing" the medium sized bluegill the opportunity to continue to grow.