I desperately want one for later ant tiers, but it seems like there isn't.

You can sort of ad hoc one together. Have a caste gate set to worker branch off of your main trail, and then a counter gate set to whatever you want, then a null trail where the caste gate and counter gate meet that leads back to your main trail. Only worker ants will take the caste gate, so the counter gate can only count workers. If the counter is full, the null gate puts the workers back onto the main trail.