Who is the owner of this pond? If it is you, or family who are on board with wanting quality fishing, you need to shut down the trespassing and poaching. It may be challenging at first, but if your private pond is open to anyone, you'll never be able to reach your goals. Work with your family to closely regulate who is fishing the pond. Until you and your family does this, the rest of the action you taking will be futile.
Your pond sounds like it is being over fished. Plain and simple. You need to limit the fishing pressure and stop the removal of bass. When that many golden shiners reach those sizes, it generally means there are few bass, especially larger bass, too many weeds or a combination of the two. I am betting in your case you just don't have many bass to control the golden shiners. I wouldn't throw those shiners into the woods though. Those shiner makes babies which are prime bass food. Let those "cows" stay in there and make babies to feed the new bass the remaining bass will hopefully make once they stop getting removed from the pond by poachers.
So, first: Limit access to your pond. If it was me and my family pond, it'd be only my family and close friends who were only allowed to fish when I was present.
Second: Work with your family and get weights and lengths of all bass and bluegill caught from the pond. Calculate the relative weight on these fish. This will begin to tell you which species and size classes are and are not getting enough food to eat. It will then begin telling you if you do in fact have too many smaller bass and need to remove some so they can begin growing larger to replace all the poached larger bass. Keep in mind though, you may in fact have some larger bass in your pond. However, with the heavy fishing pressure your pond has been seeing, they have gotten very smart and hard to catch. 5 acre ponds can easily be over fished if everyone and their brother fishes in them.
Third: Any other species present in your pond besides bluegill, bass and shiners?
