icanon, you have an ambitious agenda! We found that although there is a lot of boondocking in the Western US in the national forests, there is not as much in Canada, at least in the areas we wanted to visit. I would recommend posting inquiries in the Canada/Alaska forum -- there are quite a few experts on Canadian boondocking who are active on that forum. They will give you some great advice on how to avoid the logging trucks that speed through the back country.
But take heart -- the campgrounds in the national parks and the provincial parks are pretty nice, too -- well-maintained, spacious, and well-located. For example, this was taken from our campsite in Peter Lougheed Provincial Park, south of Canmore:
With reference to astronomy, we found that the skies in BC and Alberta were plenty dark, even in the campgrounds, as long as you are not too close to a major town.