I also place the Acurite on the cool side with the probe under the warm hide. I place the thermostat probe on the outside of the cage either taped to the Flexwatt/UTH or very close to it. Then adjust the thermostat temps until the Acurite temps are where you want them. It'll likely take a bit of trial and error until the temps stabilize, but when you're finished you shouldn't have to fool with it anymore.

Oh, and a differential of 1 degree is fine.