I think we might use a different approach of the patching, since I've got to know there's another similar product that replaces the default vehicles_airport.bgl, so it will be a nightmare keeping track of all of them, and maybe their updates.
It would be better to *scan* the .bgl file, and search for the default pushback guids, and patch them, at their actual binary location. It will be a bit slower, because the whole 17MB file needs to be parsed, but will surely work with any present and future vehicles_airport.bgl.