I had a REAL Life situation with exactly this problem recently... (end of May) when the Discovery I was useing had a key mis-function whilst we were in Scotland...and for a while it looked like we might have to be Towed.
...Vehicle...Passengers...Boat/Trailer and all the whole kit & caboodle 500miles + home!
I would say We do have the Full "Top of the Pops" AA cover through the Bank.
Their engineer turned up sorted the main problem..
Me!...locked inside the vehicle! After recovering the Boat.... (which for some unfathomable reason everyone found this most amusing!)
Although It was soon found to be still malfunctioning!...so he rang head office and immediately received the go ahead to Convey the Boat (7m RC) the Vehicle and passengers the next day..(by now it was 8pm) and considering we were in a pretty remote area of the West Highlands I don't think they could have done more.
I'm glad to say the problem eventually sorted itself...and the Tow ect was indeed not needed.
So I really don't think..,IF YOU HAVE THE RIGHT COVER there is anything to worry about.
The AA are by far the biggest and judging by this and other occasions and experiences over the years I've used them ...they are STILL the Best!
And I for one would certainly recommend them for Boat users!