Get the thermostat ASAP for the snake you already have. Unregulated heat pads can kill them- thermometers only let you know after it already may be too late. There's another thread on here where a poor snake got hurt by a flexiwatt malfunction and it's showing signs of neurological damage.

There are thermostats you can get with more than one port for multiple tank/rack options- even if you don't win a pastel you can pick up one of them so you'll be covered for any new additions in the future.