May I ask how this worked out for you? As I am buying the REDARC /Redvision setup, in the near future, so I feel I should make sure to address this potential issue as well.
It has worked out well, I ordered some 25 Watt heating pads from Amazon, which I placed into recesses I made in the bottom of the battery box. Unfortunately RedARC does not allow their temperature probes to control any of the outputs as it would be nice to have it directly controlled, hoping they will updgrade the app one day. I installed a snap disk thermostat that closes at 35 degrees and opens at 45 inline from the programmed switch on the RedVision and before the heater pads, that way when we go on a cold trip, I turn on the switch on the RedVision and leave it on for the trip, when temp drops the t'stat closes and turns on the heater. When not using the rig, the switch is off so the battery does not drain when parked in cold weather unattended. I also have one of the temperature sensors taped to the battery and set to trigger an audible alarm if it gets below freezing in case I forgot to energize the system.
The new smaller Redvision system "Rouge"
TVMS Rogue is supposed to be out this spring, pretty sure it will run the same software, but would be good in a Jeep and has 10 outputs, 8 inputs and two tank sensor inputs in a much smaller and lighter footprint. I am on their waiting list, but no updates on release date yet.