We went through at Port Huron/Sarnia and across through Toronto and reentered at Ogdensburg, NY on our way to Bar Harbor. We spent a night near Brighton, ONT at a provincial park. Also, we did spend some time in the NY Adirondacks and down near Saratoga on our way to Bar Harbor.
We've also gone over at Sault Ste Marie. Both times going into Canada was no problem at all. Both times coming back into the U.S. was a bit of a pain. Smart mouthed agent at the Soo didn't like the music on the radio (not loud) and threated to search us, but didn't. In NY they had us pull over into a long building, made us get out, and ran our vehicle and 5th wheel through some sort of x-ray machine. I can understand security, but the Canadian agents were very friendly when asking questions, etc. while the U.S. folks must have taken their grumpy pills that morning.