We know that cars has to be inspected before starting on a closed road. We also know that ambulances etc. have to be there.
Why don't you phone or email Markus Lex (US Command of the Players Run) ?
markus@playersrun.com
phone: 303 549 3249
He can answer all your questions. By the way, it would also be much more helpful for the police etc. if you ask Markus first. Then you know that Players Run has legal road closures and also your other questions would be answered.