Mexico doesn't have an easy first year; he might get a second build with Texas, but Spain can prevent that by bouncing him in GoM. But after that he gets steady growth in the north west, and can fight Spain and/or UK for expansion in central America. And Hawaii is waiting in the wings as well. Later on Mexico can be slowed by having home buiilds only, but it's the uncontested growth in years 2-5 (approximately) which are its real strength. His only opposition in North America is UK and USA, who are a long way away (apart from the New Orleans fleet) and are almost certain to concentrate on each other. If UK doesn't go for USA what else can it do?
So why not a new power in the North West, starting possibly in Alaska, Oregon and California? That immedisately changes the balance in the north. It provides alterantives for everybody - west v east, north v south. The one problem is that the new power has no neutral at all to go for at the start, and a new one might need to be created - possibly further north than California, leaving Cal as a neutral.
If eleven powers are felt to be too many, then we could consider removing one in the south, where things are very much more crowded; but I'd prefer to see that left alone for the time being.
Thoughts?