The installation was done by a local rv dealer who is now out of business due to family reasons. Otherwise I would have asked them. My understanding is that the Stay Play Duo is powered by the motorhome. I also am aware that should the car become detached, it would have no brakes without a seperate charge line.
That is why the disconnect should go on the POSITIVE cables, not the negative cables. GM will always recommend the safest method because they have no way to know the competency of the owner and some people may actually disconnect the cable manually each time instead of using a switch. But GM also does not care at all about equipment (supplemental braking systems) that they do not offer for sale or install.
With the disconnect switch on the positive cable the ground cable remains connected to the battery. Then the Stay-IN-Play DUO or other supplemental braking system gets connected directly to the battery. The charge line from the motorhome is connected directly to the battery.
I have also read that these separate lines have caused serious issues with the equinox computers and not recommended by Chevy.
That's total BS. Figure out who wrote that and start ignoring them. Chevy's towing directions prior to the 2023 was to install a separate charge line. We have one on our 2020. Heck, their original towing instructions for the 2023 also said to install a charge line.
But the 2023 and later changed from an engine-driven vacuum pump for the power brakes to an electric vacuum pump that is "always on". That was done to provide power braking even with the engine stalled out.
But that system caused problems when flat towing in extended turns like cloverleafs. The front tires were slamming back and forth and smoking the tires. GM's later fix was to configure the car for towing and then disconnect the battery.
