Can you pre-pay or use the online check-in for Alamo if you are using costco discount codes? I am assuming not since you may have to show your card, but wondering if this can be done at the exit booth. Would like to speed up process and use the self check kiosk, but really don't the difference between their pre-pay, online check-in and kiosk check in. ANy help would be great. We are using costco corporate ID and discount code for booking. Thanks.