I've been towing 6500+ pounds through the Coquihalla, Fraser Canyon, Crowsnest with a 1/2 ton for close to 15 years with different RV/s. One of my RV'ing partners tows his 30' trailer with an Armada without issue... Would it be easier/quicker and maybe more fuel efficient in a 1 ton? sure. but still safe and reliable with my 1/2 ton as long as I hook up proper and take my time.
The weight is nothing new for me and a lot of other 1/2 tons out there. With all that said, towing a boat this size is a new experience for me for sure so maybe it tows differently? So far through the city it's all the same, I doubt it will be that much different on the highway...
but, if you plan to pull the max weight while driving 120k/h and passing other cars and stuff, then ya maybe a 1 ton is for you.
I could be completely wrong about this but I don't think an RV salesman is allowed to let an under equipped vehicle tow a newly purchased trailer of their lot? Of course that could have been a sales pitch.