Your vote wanted — what’s the fair thing to do?

I’d create an Ann Althouse-style poll here, but, well, I haven’t yet taught myself how to create polls.  So please give me your opinions in the comments.

I’m currently managing the popcorn sale for the Cub Scout pack.  Yes, I know it’s overpriced.  People fork over $10 for a bag of caramel corn (not even a tin any longer) to support Cub Scouts, not because it’s worth $10.  And yes, we’re in an upper-middle-class area so most of the families could just raise the fees to support the activities rather than needing the fundraiser — but not all the families around here do have ready cash, and, besides, the profits are split 50/50 with the Council (which would ordinarily mean the entire northwest suburbs of Chicago, but now most of the councils in the Chicago area, except for the wealthy-enough-to-go-it-alone Northshore, are combining, so I think the profits are shared Chicagoland-wide, so we’re now subsidizing the City and south suburbs/Gary area).

But anyway, we’ve been selling popcorn at the library and a local grocery store as well as asking the Scouts to sell individually, and each Scout who works a shift at a “site sale” gets credit towards the prizes (which, since I’m running the sale, aren’t the crappy prizes that the vendor provides, but are a sort of create-your-own-prize, with the alternate, “pack gets extra commission,” approach). 

My initial plan had been simple:  total each scout’s hours, total the sales at all the “site sales,” and prorate.  It’s simple and it’s fair, because some sales were much more profitable than others.  It also doesn’t penalize a kid if they worked at a “shift” where there were other scouts, too, vs. being the only one (since this generally can’t be helped — you sign up, and don’t know whether anyone else’ll sign up with you or not).  But now one of the pack leaders has said that he assumed each scout would get credit for the specific sales they worked.  And, being an actuary, I tend to overthink things.

There are three choices:  either my initial “prorate over the total sale” approach, or “prorate on a per-day basis,” or, third, “prorate on a per-shift basis.”  My own kid does best in the per-day or per-shift bases, because I carted him along to fill in holes so it was always just him, and he wouldn’t need to split the profits with anyone — but I don’t want the other parents to think I’m choosing the method that gives him the highest prize.

So, which would you choose?