Fall colours should be heading towards/in peak season. Ontario fall colour report or some such site name gives colour change by region by week as fall progresses.
I am not all that up on what to see too far up the Peninsula. I have a childhood pal who runs a grocery store in Meaford, so that is where my visiting to the region is focussed.
The county roads heading south out of Meaford -toward Rocklyn and a bit further south go over a pretty good sized rise of land that splits the watersheds. A topograhic map will show that there are many vistas available for sweeping landscapes to be captured from.
Ontario Parks web site gives the provinical park operating seasons and services. The closest provincial one is at Sauble Falls. I have not camped there myself. A bit too close to home, and I tend towards Algonquin area when hunting fall colours.
The other camp provincial park further east is at Craigleith, and here you are squashed against the highway.
There are still a few echoes of Collingwood's now demolished ship building industrial past. There is a huge pier out into the lake with old elevators on it I seem to recall, but they might be cut over to condos by now.
There is an ontario waterfalls web site as well - Waterfalls of Ontario, that gives a catalog of what to find of that sort in the area.
Good luck with the trip and planning for it.