I think you're looking at this all wrong!!!
Hook the sprinkler to you chem pump, place on roof and let it fun for 3-5 minutes (or to achieve the gallons of chem you typically use + a little extra to compensate for the sprinkler being new to all this!), after set time, switch sprinkler to fresh water and let rinse. All the while, sit in a comfy lawn chair with lemonade in one hand and hose in the other. Aim lemonade at your lips, and hose at the perimeter of the house!
Do a quick walk of the roof while removing sprinkler to look for any parts that might get missed. Work at night so customer doesn't loose respect for you!