Whatever you do DO NOT depend on GM's roadside assistance.
Our 2009 GMC Sierra broke down while we were on vacation with our trailer. The truck was 2 months old with less than 3000 miles on it, Onstar was aware that we were towing a trailer when they sent the tow truck out to get the truck.
I ended up leaving the trailer on the side of the road, I had to pay for another tow truck to get the trailer off the road to a campground. And to add insult to injury GM's idea of a suitable loaner while our truck was in the shop for a week was a Chevrolet Impala. Needless to say our vacation plans had to be canceled.
Gary