Jay,
I don't believe it is the water temp itself that stresses your fish. However, warm water holds much less dissolved oxygen, which then leads to problems.
Your average DO of around 5 is probably putting your LMB in the "stressed" range. Further, the larger bodied fish usually suffer more under low DO conditions than the smaller fish. Your skinny bass might have enough food supply for good growth, but the Georgia heat and summer low oxygen may be stressing them during a season when they should be growing rapidly.
IMO, your biggest problem is that your pond is much more shallow than the optimum design. If you ever do have a fish kill (and money in your family budget), you might consider deepening the pond if you ever decide to "start over".
However, right now I think the best you can do is optimize your aeration efficiency.
You might want to start a new thread under aeration, and give a full description of your pond and your system. We do have some aeration experts that might drop into your thread. Or you could read through the archives for old threads on the best way to aerate warm, shallow ponds.
Good luck on your project to make your fish more comfortable! A 1-acre pond in Georgia should easily produce LMB MUCH larger than 3# if you can get their conditions a little bit better.
