Since there seems to be a need to promote unity and co-operation among players in countries, how about a positive system rather than a restrictive system.
For a country that is outnumbered by "X" percentage:
Extra perks and points are awarded to a player who successfully creates a mission that is filled by players and executed. (promotes leadership, charismatic hard core leaders are needed to make the country grow, and grow stronger)
Extra perks and points for participants of said mission.
(promotes co-operation and participation, help encourage
players to grow together as a team)
Prices of perk planes substantially reduced when used in a mission.
(allows an extra advantage for an outnumbered country to create
and execute successful mission)
Outnumbered countries bases, towns, and strats hardened in proportion to the imbalance.
(allows them the chance to defend easier, and a chance to take the offense because their territory is a little tougher to take)
In this way, the country that is down on numbers gets multiple advantages, hence leveling the playing field somewhat, without handicapping other players and taking some of their fun.
I never wrote the sort of code that AH uses, I only wrote CNC machinery codes, so I do not know how difficult it would be to code.
At least, rather than whine, complain, or criticize, I've made an effort to provide an alternative solution to better the game without punishing anyone.
Make of it what you will.