When you say the trucks are mostly on the south side, do you mean on the 132 from Perce to Campbelton to Mont Joli?
I was thinking of leaving from Quebec city, so taking the 299 would seem like a big detour, going up straight north again. There doesn't seem to be anything in terms of any service on that road either. I've driven the part from St-Anne to the Parc and didn't find it particularly appealing.