Say that I am towing my friend's new travel trailer with my pickup and hit a low hanging tree limb and destroy the trailer's electric awning. Whose insurance pays, minus the deductible, of course. ...
IMHO, it depends on whether you are doing it for money or not.
If you are towing her TT for a fee, then you should assume all risk. If you are doing it for a favor and if I were her, I would not ask you to pay for the damage and let my insurance taking care of it. Any problem with insurance, I would pay out of my pocket. It's just me.