Quite true, Fyron, it does put a limit on the component of one per ship unless the modder plans things out very carefully.
Also, I've done some testing and have only been able to get the "Get_Design_x" functions to work in the VehicleSizes file so it is not as good a workaround as I had thought.
It goes right back to we need to be able to add our own dummy abilities, either in MainStrings or as a separate data file that the game can parse.