The only problem I see with your idea, is a GOOD gallery is like FPA for a site, that's why I always tell people 1 sponsor per page.
So, if your sending them to FPA with a bunch of different sponsors on it, you have "broken the chain" so to speak, from your gallery pics to the sponsors sign up page. However, that would be a good reason to put a blind exit sponsor on that page because it won't sell much else...
However, it seems like a backwards way to try and make a buck?
BTW- Some TGPs might not like the aggressive nature blind sponsors have to take from your page. In other words they may not be able to get back to the TGP without alot windows popping.