I'm not sure you're getting my logic, Butch. First, remember I'm talking about only pure double dippers, SM/ITA, ITx/STU. Not shared cars. And I'm really only talking about normal regional races here, not ARRC, Pro races, etc.
Your note on insurance per "car" wasn't clear, so worst case I'll assume that the incremental cost to the region of a double dipper is Sanction+Insurance~$50. That should cover the occasional extra trophy too. Let's assume someone who drives two sessions won't eat more food at the party and might even be too tired to drink as much beer.
Track, workers, party, etc are fixed costs, these don't change whether SM#27 runs an extra session as ITA#27 or not. And the driver has already made a contribution to the fixed costs with his first entry. I don't see an incremental cost whether workers are dealing with 20 cars in a race or 23. I'd actually argue the workers would enjoy having a few extra cars.
What I am doing is challenging the notion that the price we should charge is the full "value" of the session and then discount it a bit to try to encourage double dipping. I am saying that this does not work and does not encourage double dipping. Drivers don't see double dipping as providing a full entry of value and they don't need the extra track time.
What's the downside to charging a much lower price for DD? Lost revenue. How many double dippers do we normally see? 3? So let's say that is $1,000 of entry. Now if you charge $125 and get just those same three dd's then you've lost $600.
What's the upside of a much lower price? Potentially more entries and potentially more revenue. I could be wrong but I don't think you'll get the same 3 dd entries at a much lower price. I think you'll get more. Enough to make up the difference in price? Maybe, maybe not. But even if you get only 5 or 6 dd entries instead of 3, now your lost revenue is very very small. And, you now have more entries.
Which brings me back to why I think it's worth the relatively low risk. The entry multiplication effect (EMP). I strongly believe that what drives higher entry numbers is higher entry numbers. We all see it, when a race has 1 or 2 entries, people are reluctant to enter. But when you see 4 or 5 entries, interest builds and it becomes 6 or 7 entries. So in addition to getting more double dippers, I think you'll get more regular entries too. Which has upside revenue potential in addition to just the joy of seeing more cars on track.
ITFest isn't the perfect event for this idea. ITFest already uses the EMP to drive entries. ITFest gets big entries because everyone knows it will have big entries, the EMP effect in action. A better example is a little regional race with 4 ITA cars. Who wants to tow up for that? But make that 6 ITA cars and maybe it's worthwhile.
That's all I got, anything else and I'm in danger of