Sounds good to a point. What happens when there are "enough" butts in the seats? Stop the vote or keep going? This is where it turns more into a popularity contest than a sport. I still think BBing is a sport where the "best" physique wins, and usually does. With 10% vote by the crowd, you have some true fans who vote for the best, and the others who vote for the "sexiest" or the "most friendly" and this is where it spins out of wack. But, you probably don't care about the contest since your plan is only to get butts in seats.
What happens if a normally 18th BBer gets upped to 14th due to his insistent peddling and putting butts in seats? 4 guys still robbed. That's where you have to make it like 5% or less, to where it makes almost no difference. In the higher placings it would make all the difference, since they're so close usually. Lower placings, probably not, depending on the % and how many "friends" the BBer made. I get the idea, and I'm all for getting BBing out there, but this idea has a long way to go.
The fans could participate in another way. By getting mic time and telling the crowd/BBers/promoters their thoughts on the show. Or, they could be given prizes and hold mini-contests of sorts. Like arm-wrestling or something. Or have a "half-time" cheerleading routing if there are gaps inbetween parts of the contest. Things like that, where it's enjoyable but doesn't take any seriousness away from the scoring.