None of the autonomous mode features are currently designed to be without active human interaction. Can you do it, pretty sure it can be done to some degree, but remember you are using software that is not fully perfected yet and so I would have serious reservation doing so normally and would have significant reservations with several tons of RV behind me that the system was not designed to manage. Should a crosswind hit and push the trailer, it is yet unknown how the vehicle would react and in the event of an incident, logs can be pulled from the car to see if the interaction was present.
Bottom line, I would not do it, nor do I know of any autonomous consumer grade vehicular offering that does.....yet.
Super Cruise as it's called in GMland, IIRC requires hands on the wheel, unless it's evolved from last time I saw it in action.
I am aware that testing on tractor trailers is ongoing and farm equipment has been doing it for years, but also has satellite guidance and those are also not moving at 60+mph. The tractor trailers might be, but then again, those were purpose built, whereas the consumer gear is more supplemental convenience than full autonomous for now, hence the do not do it from the manufacturer(s). In fact there may even be laws against doing so in the current offering.
Regardless, if the manual states not to do, and you do it and something happens, and there is personal injury outside of your party (or worse) and your vehicle was at fault and said logs find you were not actively participating in the vehicles control any ambulance chaser would gladly take on that kind of case, and a DA depending on severity might also take on a reckless endangerment or involuntary manslaughter case.
Of course when they say it's ok to do, you're off the hook...more or less.