Don't tow a car, but I think you have to have the ignition in 'on' so the steering wheel remains unlocked. Having the ignition on will keep several gadgets on also, and they recommend disconnecting the battery in order for it not to be dead when you want to use the car.
On a new car, if the battery won't last for several days, with AC and other items off, there is a separate problem. Also have to remember to have the headlights off "auto" if so equipped.
Again, since I don't tow a car, I may be wrong on all this.
'05 36TK3 Mobile Suites
'10 F450 new to me
'09 F450 Lariat 4x4--died