We had a heads up show a few years ago. Street tire heads up. They had 5 fast cars show up and a couple of guys in 14-15 sec cars buy in at the last minute to get the qualifying money.
Our track does a Tues. night street car t&t. A couple of years ago they started having a shootout. The fastest 16 cars would get a sticker and the top 2 would run off for a trophy. A local forum was had a ton of posts about "Yeah the way racing should be. Heads up no stupid bracket stuff."
All these guys with their mustangs, camaros, and imports started bragging about the decals and trophies they were going to get. I didn't take long for a 9 sec vega to show up and the whining and crying began. "That's not fair!" "they should have weight rules" They should have back seats" Blah blah blah. I've seen nights you have to run 10's just to get a decal. Last I heard the track record for that event was like 8.70 .
Heads up racing is just a money pit. The class will always get faster. They people with money and the want to make the changes will always be faster. Sooner or later the "slower" guys will get tired of being beat and quit coming.
If you think a class like that will work, approach a local track owner and suggest it to him. See if he would add it to a night. A lot of tracks would give it a try. You might try to find someone to sponsor the event. Like a local speed shop.
If you're really brave, Look into renting a facility one weekend or day. We did a big motorcycle event at a track a few years ago. They agreed to have it if we put it together and promoted it.
It might work in your area but it has never worked here.