More experimenting with my foot. I had 15 minutes to warm up for a killer weights/core class, so I warmed on the TM for 5 and then did one minute intervals for the next 10 minutes, with a 2 minute cool down. The intervals were even ratios (1 minute run at 6 mph and 1 minute walk at 4.2 mph). My foot felt fine, and even better, I felt in control of my breathing at 6 mph. I kind of modeled this after a trainer workout I do on my bike.
My foot was fine after, during the class, which had a lot of balance and foot work (squats, lunges) It's a bit tender now, but I think, this is the way to go to increase my tolerance on the foot and also my tolerance for running (again).