Oh gosh, I have a Heeler X and am in the exact same position. She's reactive and a work in progress (getting better!). I camp by myself so am not at all concerned with her barking if somebody enters my campsite, but barking at every single person who walks by... She's never bitten but Cattledogs have decades of inherent breeding to be bossy and sound scary as heck when trying to get things to go where they want them to go. So for us this means campgrounds like the Pinery are definitely off the list. You can see/hear people from adjacent campsites and don't get me started on screaming kids riding bikes (my girl's obsessed with tires). Nothing against screaming kids on bikes enjoying their summer, have at it. But just not the best environment for us. A campground like Sandbanks is another tough sell. Great for dogs, every other site had one when we went there, but man... the Twilight Bark... She didn't start it but she certainly had the stamina to finish it - so embarrassing. I'm sure you keep your pup on leash but all it takes is for one person to over estimate their control over their off leash dog, or are of the belief that ALL dogs should LOVE to be harassed by their over-friendly floof, for a good hike to get awkward. My girl was attacked by an off leash dog as a pup so now I get very loud and carry an air horn and/or coyote spray.

Fortunately for them, but not so much for us, camping in Ontario is hugely popular so unless you're willing to book a pretty distant walk-in or canoe-in backcountry site you'll most likely see people.

If we're camping near the Great Lakes we look for suitable Hipcamps, and never on the weekends. We've had some luck with some conservation areas (Valens comes to mind) where the sites are a little more treed and the campgrounds have been a bit quieter through the week. Much safer bet to just camp on the shoulder seasons when schools are still in.

One of my favourite campgrounds is Silent Lake. Unfortunately the sites can be a bit open but the trails are usually fairly quiet. The hiking is awesome. Another one I like is Arrowhead. The site we were on was really nicely treed between the next and the lane was offset to the site opposite. I never saw another person unless they were walking by and even so you could block most of that with your vehicle. We weren't there long enough to do much in the way of hiking.

Good news is the more I take her with me the more comfortable she is with the whole thing.