I actually did this once. used PVC with a tennis ball at the end and painted the tip of the pole red. Wore back sunglasses.I just stick a white cane out the window.
run it out the window while I was going through a drive through with the dog up front in a harness....told the cashier to make sure she handed any change back to me one denomination at a time so I could count it, then I would show the dog each bill and ask if it was the denomination she said it was.