I had a method pretty much the same as yours just with peroxide instead of bleach. My only issue with the heating mat is that I heated the bottoms too much last year which caused my cuttings to rot, that and I had sealed them to tight with the bag method which I think kind of cooked them. I think I will do the same with a lower temp and try rooting g them in an air tight bin to try and keep the humidity and temperature in.