Given your preference for nature over “the big smoke” would definitely avoid Toronto and Montreal unless there are specific things you would like to see/do.
Would definitely recommend a bit of time on Vancouver Island - it’s gorgeous. Do you fish? If so going north on the island should provide some fantastic fishing. I think with a bit of planning getting around on Vancouver Island via bus should be doable - but obviously you would be a bit restricted.
Have you looked at doing the train trip from Vancouver to Calgary? Have never spoken to anyone who has done it who doesn’t rave. I have not done the train but have driven virtually the same route a couple of times and the scenery is speecy. If you do arriving in Calgary will give you plenty of options to fly east.
If you want to avoid the big cities consider flying into Ottawa. The Ottawa ballet is very nice and you can decide to head either west into Northern Ontario or east into Northern Quebec. Both will provide plenty of nature for you.
You are going at a great time of year for all of the locals you are looking at.
But again I stress it is a big place so I recommend you do a bit of research and pick what you want to see, rather than “going” to a bunch of places and not “seeing” much at all.
