How far North in Michigan are you? RT may be possible year-round for you. If not, they can make a great Fall-Winter-Spring bonus fish.
I'm in Howell Michigan, which is generally hot for about six weeks from mid July to September. ie 80 to 90 deg F high daytime temperatures. Would the deep water with aeration be sufficient to keep them happy? The water flow into and therefor out of the pond will most likely stop during that time except for heavy rains. I do have a large 30 acre watershed feeding my pond. Most of my water source comes through an underground county drain. It is cold when it flows but I have not actually measured the temperature of it. The drain is about 3' below grade and flows into my small detention pond before going into the main pond. I would not expect RT to reproduce, but if they would live I would not mind restocking them from time to time.
