this is not the first time somebody has decided they wanted to do a 24 hour race at a moments notice,
I'd actually be happy to help organise such an event for demo racers, they're not all morons (usually far too young to know any better). with better organisation it would be very do-able.
my advise, set up a website (a blog type thingie would even do it) with all details of when, where and what will be racing. you'll ideally need to setup a mail adress for entries and stuff. and you'll need to find a server to use. (it'll have to be a dedicated server for reliability and speed)
the biggest piece of advice i have for anybody contemplating this sort of venture is to DO YOU'RE HOMEWORK! read the rules of the existing series' to get an idea of what is involved. it'll take a few months to organize properly. if you don't spend the time to set this kind of thing up, you'll not have anybody to race. 24 hours is a long tome to race alone.
it might be worth running a 4 hour just to get started, you'll have more racers willing to participate and you'll have a better idea of whats invloved.
good luck!