Airport vehicles surely don't drive through wings, but of course, this assumes the configuration for the airplane is correct.
If an airplane is not natively supported in GSX, you must either create a configuration file yourself, using the easy to use graphical editor (no manual editing at all), OR if someone shared a configuration file for it, download it and put it into the airplane root folder, the same that holds the aircraft.cfg
Your problem seems to indicate you reversed some passenger doors The 1 and 2 must be in front of the wings and 3 and 4 are usually behind, if you misplaced one, it's likely the relevant vehicle might go through the wings.
Another possible issue, is that you customized the vehicle positions for that parking, and misplaced the stairs locations (to be sure you are moving the right one, check the stairs name in the green/white message line on top of the screen when you select it to be moved) so the vehicles couldn't find any other path to approach the airplane other than going through the wing.
