IMO for the long term utilization of trout (and SMB, YP, RES ) probably the best plan is to continue with the plan of Fall trout stocking and harvest them before the LMB spawn in your region probably 3rd week in May or maybe as late at June 10-15?. If it were my pond in mid-Michigan and I wanted trout, I would monitor the water clarity (secchi disk) and the temperature profile as you have done so far this year. Whenever the water clarity drops to below 4.5ft with bottom water temps still at or below 68F trout do not need to be harvested. When the bottom water hits 70F harvest the trout.

Important. When the water clarity drops below 4.5ft Secchi disk in your Michigan 11 ft deep pond, all bets are off for trout summer survival; with or without aeration.

Having or maintaining a cold water refuge with clear water of 4.5ft is entirely up to you and your goals. Pros and cons to it.