Welcome Bob. I competed in the blowgun competition in Tahlequah in 2009 and loved it! Please don't ask how I ranked ;-)
Anyone equipped with a rivercane blowgun and thistle darts can enter.
I've only heard of a couple Cherokee field events being held. Specific rules would limit such events to venues capable of conforming to them. Doing the best you can with what you have available works better.
Two things to consider are the skill levels of the participants and the possibilities of lost darts. If you are using Cherokee style wood and thistle darts, this wouldn't be as great a danger but commercial darts can be very hard to locate if they stray away from the target. Yes, I admit it. I have on rare occasions missed the entire target. Hey, you'll never feed yourself with a blowgun in Oklahoma if you don't practice on windy days.
Wish I could shoot beside you in October but I'm having a rough time getting clearance from my "commander" plus the 1,000 miles one way would make for an exhausting weekend.