Re: What type of thermostat?
A Herpstat II would work well for you. One unit with two probes that can be set completely independent of each other. I have several and have never had any issues with them.
Re: What type of thermostat?
You really don't need 2 probes like that for a single rack. Just a tstat that can watch the hot spot, and the cool spot will always be a few degrees less.
But I also give my vote for herpistats.
Re: What type of thermostat?
I have both VEs and herpstats. I prefer the herpstat, since you can set temps to a tenth of a degree. If you're thinking of expanding and breeding, it might be worth the splurge for the herpstat with four probes so you could run a couple racks