Just something to consider - If the FM have had 2 years to reproduce without predation, the forage base should be more than adequate for the LMB until the BG are established. The FM will be eradicated shortly thereafter no matter how many "safe" places you create for them. You may get a greater return on your efforts if you focus on structure for the BG & LMB. It's hard to believe, but unless there is an upstream supply of FM entering the pond, they will all be gone in about 3 years following the introduction of LMB. Of course you should do what you want on your pond, but I think additional research will support this approach. Congratulations & good luck with the stocking!