The 'generic' outfit templates I don't find all that useful because they're so heavy-handed, insomuch as they overwrite everything. And have other quirks - like the 'seige' template not having any defensive weapons at all. 'Escort' and 'balanced' seem to be identical.
So whenever I use them I will almost always end up further tweaking the layout because it doesn't include what I want, so they're no faster than doing everything manually.
If you did use a dynamic list, you wouldn't need every possible config on there.
You don't need to put any of the 'base/default' configs on there at all tbh, because if the player is refitting a captured ship they will always be changing the config away from that layout (otherwise they wouldn't be refitting it), so what what's the point of saving that?
All you need to do is save the layout when the player okays the design - that's what goes into the dynamic list.
Then it's as simple as open designer, pick "copy <ship type> layout", apply. Done.
And if you want to be strict about it, the list can be culled whenever there is a saved layout with zero active ships of that type.
My personal preference for handling this would be unlocking a design template for every foreign ship type you capture.
You can't build ships from it because you don't have the nesecessary means to duplicate the parts/processes etc.
But you can refit ships to it.
This would then allow captured ships to be mass-refitted (either by cash or industry) in the same streamlined manner as 'native' ships.
It doesn't really matter if it uses templates, lookups or literally any other means, so long the end result is copy layout of <ship A> onto <ship B> so captured ships can be repurposed without having to manually change every component, I will be happy with it.