Here are three of mine. Two kart tracks and another road circuit. The kart tracks fit on 8-12 acre lots, depending on length and provide for 200+ pit spots. The race track is designed for a tight site, has a kart track and a drag strip on site with access from inside the circuit for the kart track. it shares the pit area with the car circuit but its ample for most car events.
I haven't shown the pit exit because I am still in debate about it but probably after turn 1. The advice you have already received is correct and its something you need to think carefully about.