I mean, if you don't want to use GSX, don't use it. Nobody's really making you do it. Not really sure what you want me to tell you here. Ctrl + Shift + F12 is what calls the GSX menu up, so simply put, don't do that if you don't want to use GSX. The Majestic Dash 8 Q400 should have a manual that tells you how to operate the doors. I don't have it, so I can't really help you there. The default planes would use the default door commands of Shift + E for the main door, then Shift + E + 2, 3, or 4 for any additional exits if they have them.