If you are running fans off the Coal-Trol (sounds like maybe the 8 inchers are) I suggest you plug the fans into wall outlets for the duration of the testing. The convection fan output is still working off the normal fan speed control logic when in the MAX setting screen, which means they may be running slower or even stopped while running the feeders at MAX during this testing. We've addressed this issue in the V3 code going through testing now.
I'd light up both stokers, go to the MAX setting and bump it down to 30 and let it burn for 30-60 minutes so the fires settle out, checking the temp at the fans as you think appropriate. If there is more room to go up, start bumping that MAX setting up as you think appropriate. Leave enough time (15-30 minutes) after each adjustment to be sure the fire and the stove have settled at the new temperature that rate will produce. The thermostat will remain on that MAX setting screen until you move it off of it with the menu button, running the stokers at the rate indicated reagrdless of the temperature.
Of course, during this your house is going to get pretty hot, open windows as necessary.