I agree that the starting O-line will be:
RT: Tauscher
RG: Spitz
C: Wells
LG: Colledge
LT: Clifton
As for the back-ups, I think we'll only carry three: Junius Coston, Tony Moll, Allen Barbre.
McCarthy said that Moll's footwork is what you see from Tackles, and that he'll figure in at RT or LT (mainly RT according to McCarthy). Coston has some experience at C and G, so he provides good cover for Wells and Spitz. Barbre is a LG, but I'm not exactly sure why because I don't foresee Colledge moving anytime soon.
In my opinion, Colledge isn't ready to be a full-time LT yet because he simply isn't strong enough. I think he'll be able to play that position in a couple of years time, when he has gotten more reps and gained more strength. For now though, I see him being mainly playing LT when we are in a 'worst case scenario'.