I think all the shops should have an old Commodore parked round the back for customers who want fuck in the car service, or maybe a panel van/shaggin wagon.
I think some guys would go for it.
Also they should have a fuck on the washing machine service in the shop's laundry, fuck in the waiting room in front of everyone service for the exhibitionists, fuck in the courtyard or laneway for the outdoors types etc. Lot's of possibilities.
There would be a demand for it from customers who want a change from the usual fuck in the bedroom service, and I reckon there will be some WLs wild enough and/or keen enough for the money to do it.