GMC Troubleshooting Questions? Ask a Mechanic for Answers
Hi there, I am Cam. This is a legitimate concern. Even in the acc position, some modules will be awake and will drain your batteries in a matter of a day or faster. Add to that, when the vehicle had a couple modules awake and you start moving, it will wake up more and can turn the lights on, accelerating the drain. You will need follow what the manual says for flat towing to ensure the batteries do not drain.
It may work, but also consider the odometer will then likely accumulate mileage as well. Plus it could overtax the charging system on your motorhome. You would be far better to get 2 screw type disconnects or wire in a big battery disconnect switch if you are going to tow often.