A major problem is there not being a way a city can legally speed limit a road such that it can ticket cars who go faster than what the bikes allow assisted.

If you take away their legal reasons for overtaking you while you go as far as the bike let's you and there's nothing ahead of you, you've already massively reduced the amount of dangerous overtaking, and you can aggressively police the remaining overtaking for speeding without having to prove they are overtaking in a dangerous manner.