Since we all seem to be pondering the cash drawer situation, I came up with a scenario that could fit.
She's got the door locked already, drawer out on the counter (this would put it at after 11pm) the abductor pulls his van up in front of the door, blocking the view from the road "just in case" He knocks on the door and, since she seems like the type that wouldn't want to be rude to a customer, she opens the door to see what he needs, thinking it must be important or that she's just going to tell him that they're already closed (these are based on real life scenarios that have happened in my former life as a gas station clerk) and as soon as she's outside the building he grabs her. He may have tazed her, which would explain why she wasn't seen in the vehicle, but in reality it doesn't matter how tough you think you are when someone overpowers you. (Something I personally hate to admit, but it's true.)
From there, I don't know, but my amateur gut tells me that the lake and the sketchy hotels in the area are going to play a part in this :/