Grades of 6 to 7% can be trying, but we have traveled on 13% grades without too much sweat. Keep the speed down on the descent using the transmission (or engine brake in a diesel) and use the service brakes to bring the speed back down after it has risen a bit. We have done this both in an 04 Southwind on a WorkHorse chassis and in our current DP always with our tow'd connected. No worry about going too fast climbing :)
If you have driven the Cabot Trail you won;t see any more difficult on this route. Do watch for high wind warnings, we have seen empty tractor trailers blown over in our travels. Also if there are windsocks flying as you exit a pass be prepared for a sudden gust (for the most part slow down a bit).
