How about adding groups of countries as a new country in eRep? Those countries must have something in common and of course share border.
For example, "CentroAmerican Federation", with Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama. All those countries are together between Mexico and Colombia, they speak spanish and their current goverment system is a presidentialist republic. They could have 6 regions, one per RL country.
With this you could get a larger native base for adding new countries, or fill huge holes in the map (hi Africa!)