Your chances of running into trouble are pretty close to zero unless you're wearing a 51st State t-shirt or something.
I work with a a decent number of Americans who either moved here or are here temporarily, and I can't say there has been any tension. I think most Canadians who are staunchly anti-US are also aware that plenty of Americans aren't happy with their government. I can't say I've seen any vitriol towards the average American person.
I doubt you would have any issue at all travelling in almost all of Canada. Alberta might be a bit more US friendly.
You don't need the bumper sticker, or to apologize. As long as you aren't wearing MAGA gear or being bombastic about Trump, people won't really think much of it. I assume anyone visiting Canada isn't a Trump supporter anyways, as most polling shows they've decided they don't like Canada.
(Asking for a friend.)