Most of us don't rent tow vehicles, at least not regularly.
What not just call enterprise?
PS, I have t seen a HD pickup in the last 10-15 years that didn't have a 7way trailer plug and at least half have factory brake controllers. Going out on a limb, if they rent tvs for towing they have brake controllers.
Call your insurance, don't ask us what your insurance will cover.
If your ins covers it no need to "tell" them you're towing just to get soaked for extra charges. Just me, IMO, I'm not that risk averse. I towed a 20' trailer with a rental minivan once cause I had to and it had a hitch.
