There's no harm in spending lots of time in Canada, just reduce your mileage in Canada if you're worried about fuel costs here.
Northern Canada has wide open space with many back roads worthy of several nights of boondocking and hiking, perhaps some fishing.
We've never fretted about the cost of fuel for the 3/4 ton. It just is what it is. If you're fretting about that, it will affect the enjoyment of your trip. We prefer to cost-save by not staying at commercial RV parks, not eating out, not needing internet connection every night, doing our own "tours", getting out in the bush where there is no place to spend $$, and so forth.