Not really the airspace is one thing but commercial work is regulated in otherways.
The logistics of who, what, when and where would have to be set out.
But a mid air with two banner towing aircraft involved is a good enough reason in my book.
You would just have slot times going down the beach saves any fannying about just have them at 15 min intervals if you miss your slot because you stuffed up your uplift tough luck. Photo sorties need to be done away from the active tow line. NOTAM the tow line as well so private flights know they are going to be about
Two aircraft trying to do the same thing over the same bit of airspace without any coordination is always going to end in tears.
Marketing folk are a bunch of fannys I can quite imagine the pilots instructions are to follow the other one and try and get in front of it or some such rubbish.