As for older trucks I bought a 95 Ford F-350 duelly 4 years ago with 192000 miles on it well oiled down south truck wouldn't think twice about jumping in it and doing a cross country run with the camper. I've probably rebuilt the whole truck but it's cheaper than a new one and no emissions, as for sticker weights in Ontario they go by axle weights as per DOT as I have checked and as long as you increase the carrying weight on your ownership you are good GVWR means nothing to them as long as you don't go over GVAW weights. (Call your local DOT in Quebec and ask them)
Dave