To keep it simple, I recommend utilizing your standard inherent risk assessment to determine which risks are present and to inform the level of due diligence and monitoring required for this relationship. The beauty of using your inherent risk assessment is that it will help you objectively identify the risks and have the necessary record to support your decisions. Since they will be interacting with your customers on some level, at least some risk needs to be addressed.
I hope that is helpful, but welcome thoughts and suggestions from other members as well.