They don't need some hide away secret exit and return.
There's an entire room and structure set up to move people from the valet onto the ship. Why wouldn't they just use that anytime someone needs to move from valet to ship? I mean, for staffing and best story experience, they want you to show up during the arrival time block. But, having 1 guy working valet all the time isn't a huge deal.
Likewise, on departure day, they need a way to move everyone from the skip back down to the valet. Do we think on the last day, they just give up on the experience, open a front door, and say "HA! Not really on a spaceship, there's the valet don't forget to tip.". I'm assuming there's some reverse process where they shuttle you down from the ship to the port then out to the valet. A last set of show to usher you out to the valet and complete the illusion that you were on a starcruiser.
Given that they have to have both of those. It's completely within immersion that shuttles would leave the ship and return whenever. Always being between the same destination would be the only story hole, and that doesn't impact anyone not making the trip. So, if someone decides that the ride from valet to ship and ship to valet is the BEST part of the experience, and they want to just go round and round in circles shuttling down and back up, then why not let them?
It's not like that round trip shuttle is the same as taking a round trip tender trip on an ocean cruise. The real tender would have actual costs.