Jake,
Actually, your problem does not seem complicated at all. Most people have one or two problem fish...you have three...green sunfish, bullheads, and white crappie.
All three are very bad or very good depending on your viewpoint, at overpopulating the pond and smoothering out the BG and LMB.
Your answer to Gator's question about goals and objectives for your pond will help determine the best course of action.
There is a great wealth of info on this Forum at your disposal, and many good experienced folks who will help. As Gator said, you've come to the right place and you're most welcome here.