Good summary, but you did not calculate the effect of the Ron Paul vote - the farthest to the right conservatives who would have voted for someone other than McCain, had Paul not been on the ballot.
PS: I was first and last a Romney supporter.
I didn’t calculate the Ron Paul types, because they are hard to apportion. Some equate with hard core economic conservatives and might have gone for someone GOP other than McCain. Some were very antiwar and would either vote Obama or sit rather than vote for anyone the GOP could have nominated. Some are socially liberal (pro-drugs, pro-abortion) but economically free market types who are never going to be happy with an economic+social conservative Reaganesque coalition. Like the isolationists and the protectionists they have a very high bark to bite ratio and for the most part aren’t worth the effort required to recruit them or even to swat them. If you are true to yourself and true to small government economic policy, alas unlike many GOP reps recently, they’ll at least respect you. If you then point out the many ways the Democrats, in contrast, talk out of both sides of their mouths maybe these gadflies will attack the Rats instead.