J Hooey,
Welcome from another MI forum member! Great to hear that there are folks in the pond business and on PB Forum from all parts of MI. There were several active members from SE and mid MI but I haven't heard from them in over a year.

Sounds like you have one tremendous setup there! I'd love to see pictures of your 5 acre pond. You are very fortunate to have spring fed conditions (probably better water quality, colder water) and deep holes to prevent winter kill.

My puddle is near GR and I'm still in year 3, learning every day. If you do end up getting SMB from Laggis can you let me know? I'm interested in a few myself (a very few!) and I could meet you if GR isn't on your way back home.

I have a relative who lives in Imlay City and there is a fish farm there (google imlay city fish farm) So far the only stocking I did from a fish farm was my perch from Laggis and they are doing well in their 2nd summer in the pond here.

What other fish do you have, how is your forage base doing or are the young BG and GSF your forage? How did the GSF get in the pond in the first place? Do you have crayfish? FHM? Shiners?

It sounds like you need an apex predator but LMB can be a management nightmare unless you can put in single sex LMB.

Perhaps we can work together to find a way to ship HSB to MI. Perhaps a pond boss member can help ship small quantities of fish large enough to escape predation? From what I have learned on the forum, trucks that haul fish across state lines have too many hassles with the MI DNR to make it worthwhile. If your pond has no inflow or outflow that connects to an existing stream or public body of water then as long as we can source them we can have them.

I know about 5 years back a SE MI pond owner drove across to OHIO to pick up some HSB and found they did great in his pond and filled that predator niche just perfectly.

You should consider adding RES or long ears for variety, although stocking in your pond may be difficult now since the GSF will probably swallow fish that are stocked that are of small size.