Oops - you are correct Frank. I just did a search for 'bee repellent plants' pulled up this article and looked at the pretty pictures. I didn't really read it because I'm not bothered by bees or wasps. My bad. And when you think of it, most plants work hard to attract pollinators, so not sure what might repel them. Maybe work in an opposite way: make flower arrangements with known pollinator attractants and place those at the perimeter of the event.
The wedding people may end up with those bee/wasp traps, some of the glass ones are not as ugly as the plastic ones. Or as you had suggested, a screened tent, but those can be spendy to rent.