Make it apply only to non-home bases. In other words, if you are invading another country and your numbers are superior, you have a limited planeset at those invaded fields. Your home fields always have a full plane set.
This was actually discussed at the Con and HT felt that the way that the parameters are set for the ENY now and the voluntary moves by some, probably wouldn't require him to make any more changes in this area.
The main problem is not country numbers, its 2 countries hammering the 3rd. ENY doesn't address this other than reducing the overal numbers by pissing off players and to some extend re-distibuting some to other countries.
And this is not something that HT will change ... he said so at the con. This is what he considers a gameplay scenario and he will do nothing to change it.
The ENY wasn't meant to balance gameplay, only to balance overall numbers ... once numbers are balanced, its up to the countries to deal with where the concentrations of attacks are happening.
Also, it is the design of the map and where your country is positioned on the map the determines if you are going to be facing a constant 2 front war. Simple as that. The is no "truce", implied or otherwise that you will find that will cause 2 countries to gang 1 country.