IMHO, I don't think this would be much of a sticking point. For me, I'd gladly move to North Dakota. I'd rather have freedom and freedom from the do-gooders than warm weather or resources. And look at what resource-less countries such as Hong Kong, Singapore, or Japan can do. The type of people are the greatest resource. The red states would have exploding freedom and economic growth. I say give the "best" areas to the leftists. Those area will be destroyed quickly. Maybe those ruined areas will go on sale and could be regathered into the Right territory.
I’m not saying it couldn’t happen over the long haul, I just don’t think it’s possible for it to happen amicably, given the nature of leftists.
Think of splitting the military defense capabilities, weaponry, military bases, Navel assets, fighter jets, nuclear assets, for starters. Then there are such things as access to waterways, foreign trade embargos and tariffs directed by the Left Country toward the Right Country (including attempts to restrict access to existing ports and harbors, etc).
A civil war would be the most likely scenario.