I like having pit space personally. It's not fun when you have people's stuff all mixed in with yours.
Make sure you have plenty of Outlets.
Is there gonna be a Hobby Shop Attached or a part of the Facility? Nothing better then getting a part right then and there.
Depending on the type of dirt you will use.( Clay I assume) Make sure it receives an adquate amount of moisture daily. There was nothing worse then driving at my local indoor track and it be dry. There was no traction and it made the racers very upset about having to pay to run on a track with no traction.