Maybe rent two flags, and let the snorkelers take one?
Head straight out from the beach, swim until you get to the snorkel trail of limestone boulders. I like to start snorkeling straight out from the first bench you come to on the beach, then head west towards the taller bridge. On the way, there's a sunken motorboat that's a good size, and some shopping carts. Once you reach the sunken hammerhead statues, take a hard right and swim to the taller span, then swim around a few of the pilings as you make your way back to shore. I find that by then, most people who aren't swimming all the time are getting a little tired of all the floating and swimming and diving, and have seen a lot of cool stuff.
No problem to dive doubles at the Bridge, it's not uncommon to see technical divers doing drills there. Atleast, they try to look like they are doing drills when divers pass but as soon as they are alone, I bet they just look around at all the cool stuff like the rest of us. Though, I might have done a drills dive there a long time ago before I realized that it's just more fun to just have fun at BHB and save the drills for boring places.