A third option is to do as you suggest add female yellow perch. Now (April) in your region female YP are gravid with eggs and easily recognizable. Mature males should be thin bodied and have freely flowing very white milt. Catch some of them, sort, and add a few each year to your pond. A hatchery with adult fish may sell you some females. YP tend to get hook smart a little slower than bgill or trout. YP, since they are coolwater fish, should also grow slightly better in your cooler trout waters than bgill. YP will also thrive on the surplus minnows better than BG. However do not expect the YP to eat pelleted food as well as the BG unless they are pretrained before stocking.
