I don't care how small your company is, there is never a reason you cant afford a minimum wage worker to be there for safety. They can be on their phone or whatever, doesn't really matter as long as they are present to see and/or hear something go wrong and provide assistance whether it be calling emergency services or guiding them to the wash sink. Nearly saw my old boss get killed on video after he took the pressure washer down the tunnel to spray some things and the hose got caught in the dry n shine. He nearly got wrapped up with the hose.