One thing i found with my heat pad was that it made the underside of the dough too hot. I compensated for this by raising my dough container above the mat a bit. I used a metal cooking rack for a microwave to do this. Sort of like this https://www.amazon.com/Universal-Baking-Microwave-Convection-Ovens/dp/B00LZVF6MU

This allowed a bit of air flow underneath so it gently heated the dough.