Brian-
Interesting problem. Please keep us posted on the solution you find.
I'm too far over my head to provide a solution, but when my feet won't touch bottom I go directly to a higher authority. Have you considered contacting the maker of your strobes and discussing it with their engineers? I suspect that with your equipment/experience and company credentials they would sit up and take notice of your problem, suggesting solutions or perhaps even conducting experiments of their own. They certainly will have the coated strobes on hand, and almost certainly the right kinds of testing/monitoring equipment for evaluating the results.
Hank