Unfortunately, a single direction is all that budgets can afford. But in building an EHLS we leaving an area that private industry can expand and fill the vacuum that would be created. X Prize just showed that the potential exists. Small rockets would be the first stage of private industry filling the gap and with time launch vehicles.

I don't see that SSTO is a requirement. It would be nice but is not needed. Staging is far more efficient. Plus I don't see the point of having SSTO is we were to retask an EHLS for lunar orbit requirements.

As for the fuel requirements they would be quiet large.

Plus keep in mind that we need time for EHLS to be developed. Delta and Atlas would have to lift some of the modules to the ISS if we have any hope of ever finishing it.