So, how do I open my own thread so I can get some advice?

Ok, for anyone reading this I am stumped and feel pretty stupid and sad. I bought my first bp (pastel male for 200) about a year and a half ago from a pet store (mistake number one) Did most of the research on how to care for him properly AFTER i bought him (mistake 2) Ok so he sheds very well, I use cocohusk for husbandry because it retains moisture. I have him in a 50 gallon terrarium and he had always loved being up high hanging on leaves and branches no matter the temp. K on to my biggest problem. I use an Under tank heater with a high quality thermostat and at its absolute lowest dial the temp of the glass still reads over 100f. This is upsetting because i do not want him to burn, dry out or die. Since I have no access to heat tape today I'm wondering if i should just rip it off throw it away buy another and instead of sticking it right to the glass attaching it to aluminum or something that doesnt melt at high temps and just propping it up under the tank. And he's picky and goes off f/t rats sometimes 4 months at a time. Bought him April almost 2 years ago and was "quoted" that he was "maybe" 6 months old......I'm buying a female mojave spider for 125 today hatched oct 28 eating f/t weekly and I have a 35g tank but no heat source.... I just love bp's and eventually want to breed them. I need some help in this heating issue. I know how lucky ive been that he hasnt been burned, is it better to shut it off altogether? He gets really cold as that is the only heat source and im never ever doing the lamp thing. I live in Winnipeg btw, buying from big box pet stores is dumber than dumb. I know more than people who consider themselves experts. It's sad really but I learned my lesson and take any advice i get with a grain of salt usually. Can they die if they're too cold? And is it ok to stack the tanks on top of eachother?
Please help if you can, have had issues with heating and figured out a good method that works...
Thank you