"Under the age of sixty" really limits the field of available contenders. Even Mitt Romney fails that test. I don't know (or care) the Huckster's age, but I'd suspect he's in his late fifties at a minimum--his lack of acceptability is based on other than age.

J C Watts' name has come up a few times around here. This might be a role where he would fit quite well. He is more or less Southern (Oklahoma) and he is undeniably conservative. Another would be Missouri's current governor, Matt Blunt, who has already announced he will not seek a second term.
Seneca, circa 45 AD Quemadmoeum gladuis neminem occidit, occidentis telum est.---(A sword is never a killer, it is a tool in the killers hands)