I recently went to the wedding of a friend who is vegan, and, as follows, all the food at her reception was vegan. And it was all delicious. It was a buffet and there were plenty of "mainstream" items (such as green salad) in addition to some wonderful dishes I'd never tried before. No one had any complaints about the absense of meat, eggs or dairy. Now, I'm sure everyone expected it to be vegan but my point is that you can certainly have a filling and delicious vegan buffet at a wedding.
It sounds like you're going to do the buffet and I honestly think that's the best way to go. Then people can just pick and choose what they want that day. And if anyone grumbles about the lack of meat, well too bad. There's always someone complaining about something. If you're lucky, they just won't complain to the B&G, which would be pretty rude.