We did this drive in 2013 and yes, the quebec part was the worst with its roads weaving and winding roads and inability to build up much speed. Ours was a class c and she drove it beautifully...no mishaps, no flats. No toad either.
Hubby and I will probably do it again but wait until a bit more of Labrador is paved to make it easier on rv. The scenery is beautiful but there really aren't any hiking trails to speak of and that is what we are interested in. I plan on doing it again and turning left when we get to Baie Comeau...