Sling,
I'm not mad, I'm laying out the headaches you're leaning toward. I have organized these things, and I don't think this is impossible, I just think it's more than most would like to bite off.
An additional class is a NEW race. The "Flite Fest 2017 International Air Races " is a bit overburdened as it is with two separate races. Perhaps more some day, but an IROC class on the first year -- particularly if the airframes in the other two classes can't compete -- IMO is a non-starter. My opinion, nothing more. You're welcome to prove me wrong, but this event will further fracture the pool of potential participants.
Actually, I don't see this as making the competition as more accessible, but less. If the planes must be identical, then the price of entry is building exactly the chosen plane, with little to no leeway. It might not cost much, but the inflexibility will drive away most builders. The other two races you'll have a choice of several designs (or make your own, if you start early enough) and how you choose to build it out is up to the builder -- you don't have to be the designer to fly.
If an organized event occurs on the flight line, where that event occurs the flightline is shut down, as well as neighboring lines. That's a safety issue, and it doesn't matter if it's rocket racing or flying puppies (honestly, not sure which would be more dangerous), the lines are shut down for the duration and cleanup of that event. In particular for a "race", you'd want the line cleared of all but your competitors anyways, if for no other reason as to keep obstacles out of the way.
I'm not saying it will be too time consuming, but too much of the same thing makes the pitch for "yet another" that much harder. If you want to pirate a flightline (the initial plan for the NASBWACC was to do just that) I'm not going to be "That Guy" and run you off . . . but flightline discipline will need to be stricter next year -- for good reasons -- so the odds of a pirate event occurring is dropping. You'll probably need some level of approval for the small event.