I don't see that as a necessary option in game, but if it's easy to add why not.
For what you want, I'd just build a world with the countries I want in it and call it whatever. You'd be able to copy and paste the existing data for said countries, so it wouldn't be a huge undertaking.
I edit the World.XML pretty regularly, so I'm kind of used to it now and don't mind the work. I play only fictional and spend a fair amount of time planning a league before I start constructing it. I make custom schedules, the whole 9 yards. For me, I enjoy planning and constructing different scenario's as much as I do playing them.