I see on your profile page you have asked these same questions last year with responses...
I guess you are up on all the border requirements of moving between the two countries and all. Going into Canada means no fire arms allowed and also a clean police record for everyone in your RV... Who knows about the pets you may have aboard.
Perhaps you are well aware on all of everything that is required. I don't think you can just drive up to the Port of Entrance and gain access... Probably even worse coming back into the US from the other side in these trying times...
That would not be my cup of tea just to save a few miles on a trip...
Just thinking what I would have to do to cross the border...
Roy Ken