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.

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.