I know the newer WashPay server from Unitec would allow you to do this...even set time periods to wash (like between 8PM and 6am). So you could set something up that the customer can wash once a day/week, what wash they get or total $ amount in a SS bay. If they have a daily or weekly plan, you don't need the RFID tag, but just a
fleet card. I don't think you need to care if they pass it around either, because you charge accordingly. You also deny commercial vehicle and have them sign and clearly understand that what the rules are. Then you charge them monthly via your cc online terminal. No additional fees.