This upcoming weekend I was planning on removing my back glass (coupe)and putting in a new gasket. There is NO headliner in my car, but I wasn't going to do that until I was ready to do the rest of the interior. Is it necessary to remove the front and rear glass to install a headliner? Or is there a good way of doing it by leaving it in there? I ask because my front windshield does NOT leak and I hate to remove it, but you gotta do what you gotta do right?