Best Mans +1

We are going to a friends wedding at the weekend, which ordinarily I would be quite excited about, but  for this particular wedding I am the Best Man's +1. I'm not really sure what I'm supposed to do, and everyone else I know at the wedding is either a bride, groom or bridesmaid! I'm sure it will be fine it's just going to be a little strange going to a wedding on my own not knowing any of the guests. 

I'm a bit shy around strangers, so I have offered to help with the reception set up in the morning, to hopefully get familiar with a few faces before the actual ceremony, so I don't look like a complete sad sack. But this has it's own problems, do I get ready before set up and run the risk of ruining my outfit/ make-up whilst lugging around hay bales and bunting, or do I take a chance and hope there is somewhere to get changed, there. (Going home in between is not an option, it's about 30 mins each way.)

Though once all the set up dramas and ceremony are over, I'm pretty sure we are going to have one hell of a party, and let be honest that's what it's really all about.

Have you have been a best persons plus one at a wedding?