Thanks for the detailed answer, it's appreciated. I have also always liked the idea of belly heat for digestion as well. I think what I'm going to do is spend the extra $ and get the herpstat that handles two. Since my UTH are pretty old at this point and a bit bent since I had to shove the thermostat under there, I'll just get some heat tape as well because that's pretty cheap. Then I'll put it on BOTH hot and cold sides. During winter I will run the cold side (when she typically isn't eating much) to help control bottom heat when it's cold, and then plug in the warm side instead during spring-fall when she's eating to aid in digestion. How does that sound?

I did finally find what seems to be a good video on how to set up the heat panels so I feel better about it now that I have a visual aid. The hardest part will be to recreate how he set up his thermostat sensor. Otherwise, it shouldn't be too bad.
https://www.youtube.com/watch?v=gmrtA7t7Dcc

It's interesting that you say the BP's typically stay on the cold side except when digestion. Mine has always been on the warm side. However, now that I temporarily have a heat light above her cage for the warm side (88-90), she's been staying on her cold side (77-80). I didn't like that she's been on her cold side so much with all the issues I'm having but now that makes me less concerned. I did buy an IR gun in the early days of my BP so I already have that and have been using it.