Based on some of the information in your post, I think the YP/WE combination is an excellent start. On top of that I would stock RES as well. As far as additional predators, HSB woulld be high on my list. They too are good eating, they will not naturally reproduce in a pond such as yours, so managing their numbers is very easy. Because they take to pellets, they have excellent growth rates but will also feed on YOY perch to help keep their numbers in check. SMB would be another option. They would have to managed more closely, but could also be a good addition to your set up.
As far as forage, well that is where you need to step outside the box. Particularly if you do not stock the SMB. Look at BNM, SFS, LCS and BKF. All would be fantastic additions to your planned stocking. FHM can be stocked as well and GSH can be added about the same time the predators go in, but I wouldn't stock them early on with the other species. I would also stock grass shrimp. They will be an excellent forage for the YP, RES and smaller WE and HSB and SMB if stocked.
