I don't understand why it has to be so complicated.
I pledge to donate $25 bucks if I don't achieve my goal of either harvesting a buck on film, or filming somone else kill a buck on film.
If I meet my goal, I'll pledge an additional $1 per inch of antler taken on filmplus my original $25. That way if I win, so does everyone else, and then it's time to party.
Everyone should feel free to pledge as much as they want and for whatever goal or antler requirement they want.