I have a strategy for when I get tailgated in the slow lane and it’s not brake checking because that’s what they expect. I’ll lock the cruise control to my desired speed. They get right up on my ass and don’t back off, I speed up putting space between me and them. At this point they’ll speed up and I’ll take my foot off the gas and let the car slow down back to cruise control speed. Repeat as necessary. The trick is to never touch the brakes. The driver behind me is alternating between speeding up and hitting the brakes. Eventually they’ll get tired of it and either pass or back off