I use Quantum Green from Vacaway as my Prespray. Sometimes you have to go "ungreen" Like "Pig Out" and "Hel Gel."

No reason to become overly dogmatic about this, when you can easily leave any final decision up to each individual customer. If you believe you are reaching limits of effectiveness with a green product, you can inform the customer of this, then leave it up to the customer to advise you to either go, or not go, any further. Bring in possibly more effective synthetic products, or stick with natural products.

You can also mention that the use of less water, mitigates the waste of fresh water, and also the disposal of all the contaminated water. I have found that many of my customers find "green" cleaning as a plus, but not a deal breaker or great advantage, but I am also in Oklahoma, and may be attracting these customer by the way I market, who knows, best of luck to you.