Before being elected to the U.S. Senate, Rubio was Speaker of the FL House. I don’t think he’s “too green” to be VP. And Martinez was a DA before she was governor (like Christie), and I think she would have enough experience to be VP.
As for Evangelical Protestants “not minding” the lack of a Protestant on the GOP ticket, I think you’re underestimating the fact that, if Romney is the nominee, he’d already have two strikes against him in their eyes (he is a Mormon and, more importantly, has a socially liberal record), so they’d need to be motivated to go and vote (and bring their friends along), and if Romney picks a Catholic runningmate it may not be very helpful to that end. And if the GOP nominates its first Catholic for president ever, and he picks *another Catholic* as his runningmate? that might not go over so well, either.
As I posted recently, we have an incredible stable of potential VP candidates who happen to be Catholic (Marco Rubio, Bob McDonnell, Paul Ryan, Chris Christie, Susana Martinez, Bobby Jindal, Rick Santorum, Pat Toomey and Jeb Bush), and any of them would be an ideal choice for almost any Protestant presidential candidate, and this is the one time that we’re going to nominate a Mormon or a Catholic. Talk about bad timing.