Scott,
I’m not sure I totally follow you, but if you want full range of motion with the treadle there is a trick you can do…
You can calibrate the pedal by pressing the first 2 or 3 points at the bottom of the treadle position (heal down) and then equally space out the other points between the bottom and the top of the treadle motion. Each point is 25% of the full range…the 5 points are 0%, 25%, 50%, 75%, 100%. So, if you put the first 2 points at the bottom of the range of motion and then space the other 3 points out equally between the heal down position and the toe down position, then the heal down position will be 25% of the volume, going up to 100% when in the toe down position. Hopefully, 25% of full volume (the heal down position) will set your amp to a level just before it breaks up. I hope that makes sense…and is helpful for doing what you want to do.
-Brach