It costs more to fly to Canada than the US? I didn't know. Yes, you would find more than red sideds. Radix also frequent the area, as do non-thamnophis species like the smooth green snake, northern ringneck snake, red belly snake, northern water snake, painted turtle, snapping turtle, and a whole plethora of amphibians. But since cost is more prohibitive, this'll have to be a seperate outing
As for collecting, while I realize with some species it's the only route to gaining them into captivity, I hope this doesn't become the main goal of the trip. Perhaps with a meeting of likeminded thamnophytes, a gathering of captive bred offspring for trade could also occur instead. Being premedatated, it might be easier to work out the permits too.
Ian