In our family pond that was a predominantly LMB and BG pond, the folks couldn't stomach draining and resetting but really want YP, so while we have a different species mix, I see our situations as somewhat similar. We've knocked the LMB population way back (to I think only 2 left, for now) so that the newly stocked YP could have a chance, and we also harvested all except for maybe 6-10 adult BG to not give them a head start on overpopulating, but we're already seeing large numbers of BG YoY. Even with trapping, I think managing our BG population will be a challenge without many LMB and no other bigger predators.

All that to say that I think our pond with what will probably end up being high numbers of little BG will be a decent test of how much pressure BG (and by extension, HBG) put on YP recruitment. I very much fear that our BG will suppress YP recruitment in our pond.

Are you culling all the HBG you catch/trap? Our 0.5ac BOW is pretty clear with low alkalinity, i.e., probably less productive than yours, but we were able to harvest 129 BG this Spring and severely knock the population back. You, with SMB and HSB as predators, might have a chance at really keeping your HBG population low if you embark on a big HBG harvest this year and just keep pulling any HBG you catch in future years. On that route, the few HBG that slip through may even grow to be real trophies. I'm also thinking that if the HBG are indeed eating lots of YP fry, if you knock them back severely this year and start to get more YP recruiting (or if you just stock another intermediate year class of YP), the tables will start to turn a little bit to where the higher population of YP may start to help you by eating a few HBG.