When asked to shoot really large groups of people the best way forward is to aim for a high vantage point.
I’ve been up step ladders, scissor platforms, on roof tops and cherry pickers to get the right angle to capture the scene below. Health and safety is always the priority though, and I never venture too high and not wear a full harness and have a qualified operator to work the machinery.
I’m certainly not an aerial photographer, and I don’t get involved with drones due to all the constantly changing legalities, but I am certainly happy to use any safe and available means to get that special image for your business.
UPDATE: I am now a qualified drone pilot :-)