Pull fuse #32 I think or install a fused charge line between the coach & toad.
The owners manual for my Saturn Vue that has the same transmission and engine is very specific on towing. Start engine, Run through gears, idle in NEUTRAL for 5 minutes do Not put in Park or Reverse after the idle period (if you do run another 5 min in Neutral). Every 7 (seven) hours whether towing or not repeat procedure!!!! 90,000 towing miles & 115,000 driving & no transmission problems the BOOK must be right. I changed the transmission fluid every 50,000 miles & switched to Synthetic the first change.
Just my experience. Dennis