Seat storage bag

I had a Idea for a storage bag that would slip over the head rest of the front seats and provide a zippered storage pouch facing the rear seats of a 4 seat rzr. A buckle strap or velcro straps would secure it to the rear grab bar so it would not slip off the seat. Does anyone know if a company is already making something like this? I could have them made locally but would prefer to just buy some already made.