Great suggestion, but I have a few qualms about the symbols - First of all, there's the glaring omission of the
Shield of the Kingdom of Portugal, which is probably what works best to represent Portugal - while the Armillary Sphere and the Cross of Avis do make good symbols on their own, we have to take in mind that the former is already included in
Brazil's symbol, and the latter is too similar to
Spain's. A similar problem happens with the
Order Of Christ Cross, which would have been a great symbol for Portugal (it was used in the sails of the Portuguese caravels, carracks and other ships involved in the exploration of the seas), but, again, it already belongs to Brazil's symbol. (Not that "being too similar" stopped them from having Russia, Austria and Poland all with eagles as their symbols, much for the confusion of some
)
Great choice on the colors, although I was first afraid the blue on white was already taken by Greece. However, if they use dark blue (a la America's/Sweden's background color), it could work wonders (and be historically correct)!
Hopefully people won't think it is just "inverse America"...
I took some time to see how these symbols would look like in the colors you proposed (and in Light Green background and Red foreground, since Dark Green with Red as been already taken by Ethiopia). Unfortunately, I don't have the tools nor the skills necessary to make them actually look like a Civ V symbol, but maybe someone else will try! *wink wink nudge nudge*
However, we can have a rough idea on how they would look in-game!
I was also unable to make the Armillary Sphere, again I don't have the tools nor the skills necessary...
Dunno if it matters much, but I'll share anyway. I'll also include a Black and White version, so other people can easily paint it whatever colors they want.
Check the album!
Of all, I agree that your first idea is the best - hopefully they'll go with that!
Also, Light Green with Red looks bad! Never again!