For F/T I use a hair dryer to heat them up after they have thawed out. That usually dries them up pretty good. I use paper for a substrate, so I would see wet spots if the rat wasn't dry. It's doesn't take long to fully dry a rat.

Your UTHs really need to be on a thermostat because an unregulated UTH can get hot enough to severely burn and even kill a BP. I've seen them get up to 130 degrees, measured on the inside of the glass.

Provided each of your UTHs are the same exact size and model, you could run them off the same thermostat. Plugging that together may be a challenge, but I'm sure someone has done it before. If your UTHs are not the same, don't try it because one will always run hotter than the others. An optimum set up will have each heating element on it's own thermostat.

Temps should be as follows:

Warm side ambient and hide = 88-92 degrees
Cool side ambient and hide = 77-82 degrees

Different care sheets will have different numbers, but all should be somewhere close to the temps I've listed.