If you're like me, and navigate mostly via the "unread posts" link, it's not always uppermost in my mind which forum a post is in.
I mean, it's perfectly obvious from the breadcrumb links on the thread, once I care to look, but short of a big flashing banner I think it's going to be quite hard to impose sharper demarcation. Credit for taking the trouble, though.
Me, I always assume prima facie that a post is fantasy unless I can determine otherwise. I don't have to worry about any triggers, though, so it's easy for me to say.