I don't see a vet being added unless the Rams decide they just don't have the horses they had hoped for. Part of the reason is cost. And, a guy good enough to pick up at a very low cost is hard to find...... every team wants and needs them.
Yes, the Rams Oline is young. And very likely how they play in the first few games will not be as good as they play in the last few games.
I think the preseason games will tell us quite a bit about the young guys and I suspect we'll see quite a lot of Allen and Noteboom and Demby.
But so far, both the coaches and knowledgeable guys like Vinny B have said that the young guys have done a good job and looked the part.