I've not seen the film but I doubt it would be too difficult to do. I think the best way would be to open everyone in club tactic, ie say hi to everyone at the recption spend no less than 30 seconds with each and eject, I used it in clubs for different reasons but in this setting you would be building a level of familiarity that people would then think you belonged there.

then post a field report, I like your thinking there is a lot of emotions spinning round a girls head at a wedding, its an interesting concept deserves maybe more posts