The thing you need to understand is that there's a difference between being an "amateur" and being "green". A driver could have 20 years of experience doing track events and SCCA club racing in fast formula cars and he'd be considered an "amateur" when he entered a pro race.
I didn't realize the race you were talking about was less than 2 months away. I figured you were talking about something much later in the year.
Realistically, you need a lot more time to prepare. Even if you could pull the right strings to get "permission" to compete in this race, I think it would be a really Bad Idea.
Get some seat time with one of the track clubs (Chin, PBOC, SAFE, etc), they all run Sebring and they all offer instruction. TONS of fun, and will gain you some experience as a track driver. Start there, perhaps with the aspiration to compete in something "big" next year.