I don't think there is a way to do this, so I guess I would like to put in a feature request:
Give the ability to upgrade core ship designs. Not to override them, just to keep the same extensions and save it as something else.
I like tinkering around with the ship designer, but I have to admit I am not that architecturally inclined. It would be nice to use the cool looking core designs and retain that same look while just adding and removing the pieces of technology you want. You then could save it as something else (e.g. Colony Ship II).
Also, it would be nice to not remove all the technology by default on an upgrade but give you an option to do it once in the upgrade designer. Both sides of the argument could have their way then.
And while I'm on the topic of ship design, does the AI just use the default 'selection' of technology it wants on the ships it designs which places the module anywhere on the ship? I have seen a lot of AI ships with a big ol' trade module stuck off the side of the front hull, which looks a little odd. I haven't looked again in the latest patch however so maybe this is fixed.
