When you're attaching the probe to the bottom of the tank are you attaching it on the inside or outside? It should be on the outside so the snake can't move it, damage it, or get stuck on the tape. Depending what mats you get they might be sticky. The sticky ones I've just placed the probe to the tank and the mat holds them on. I'm not sure if the foil tape would damage the mat or not.
As far as thermostats the two recommended above work great. I use Inkbird thermostats (doubled up for the reptiles) because at the time I didn't have a whole lot of money to afford the expensive ones (and at the time I didn't see a difference between the two, now I do). I'm planning on upgrading my thermostats to a herpstat or VE model after I fix other things (like finishing a larger enclosure for my crested geckos).