As he said, Aslong as you use same power wattage heat supply you can plug All into power bar and only need 1 outlet on thermostat!
Id even suggest returning "reptimed" head pads, and look at Flexxwatt/THG tape (30$ per pad) vs prolly 10$ total for Heat tape with a much better even heating.
with 4 of those your already at 100$. then 50$ for a decent thermostat theres 150$... Hell even return the 4 "thermometers) prolly 10-15$ a piece and get a accurite($12) for the testing tub to make sure, buying a Herpstat 1 (120$ for basic i believe) or Vevarium VE-100 155$ (aswell look on local reptile forums some people sell extra/spares they no longer need for 50-100$ make sure they are accurite) with the total cost of all the "Petsmart/petco" Overpriced crap you'd be able to get a nice thermostat and thermometer and never have to worry. as light dimmers are "dumb" and don't balance any room temp changes so what could be 89 one day may be 95+next day with temp changes.
Anyways best of luck good snake pick ups =)