Hello, and to BP.net

It will be easier for me to explain the single thermostat. Since you want to run 2 separate tubs on one thermostat, the way you should do it to maintain consistent temps in both is to use the same size tubs with identical heat sources. Some people use Under Tank Heaters(UTH) and some use Flexwatt heat tape. Whichever you choose, set the tubs up the same. The thermostat probe will be mounted to one heater, but both will be plugged into the thermostat. So basically, the thermostat is sensing the temp of one heater, but both are switched on/off.
With that double t-stat set up they are wired together so one acts as a back up so both probes have to go to the same heater. I would suggest starting out with a single thermostat and 2 tubs. Keep it simple. Once you order the rack then go with whichever thermostat will best serve your needs. Then you will always have a spare thermostat in case you decide to get a snake that has different temp requirements than the BP's do. I'm not sure what Boaphiles turnaround time on just a thermostat order would be but it is an average of 6-8 weeks on cage and rack orders. If all you need is a thermostat then I would suggest Reptile Basics. They usually ship out the next day. Hope this helps...

http://www.reptilebasics.com/