Had to work early today, so took off early. Ended up stopping by the camper (couldn't help myself!).
Here's a picture of the heater pads adhered to the bottom of both the grey and black tanks, as well as wrapped around the dump lines (look on the drain line at the left edge of the picture).
The brand name on these is Ultra Heat Inc. Their website is located here: http://www.ultraheat.com/ducted_vs_ultraheat.html
Details gleaned from their website:
TESTED TO: Minus - 11° F (-24° C) Cold Room
Power Switch "ON" OR "OFF." Tank Heaters turned on will automatically operate with Thermostat Control:
On at 44° F (+ 7° C)
Off at 64° F (+18° C)