Remember the original selling point of the shuttle was the concept that essentially everything could be re-used and thereby saving the costs of fabricating a new vehicle for each mission. Can the proposed systems do that? If not, they'll come in for the same criticism as the launch systems of the mid 1960s. The bean counters will hammer them to death.
The Saturn V was a monster, but you're right, it would be the only way to go. And you're also right about the fact that the SV is a big, disposable monster as well. You couldn't just dump it in the ocean, either, as it would have to push the Shuttle high enough so that it would burn up on reentry from a low orbit.
The Enterprise had a booster cover, if you'll recall. One could probably remove the valves, then cover the ass end with the aerodynamic cover.
Speaking of which, do you think they'll have to pull Enterprise out of mothballs? At least to cover the shuttle missions that need to go up in future.
Be Seeing You,
Chris