That's a good hurdle. No need to go LH2 compatible. Accept a cheaper technology that can go with kerosene or propane, and save some structural volume while you're at it.

And while you're doing that, ditch SSTO and reuseability which are illusory diversions, and try multi-stage expendable solids. They're only glorified fireworks rockets. You can have a room-temperature no-frills LEO booster quite cheaply.

(I realise there is far more to it than this, but we have to start cutting the Prima Donnas down to size somehow. If we can save 10% on booster cost, then the precious self-serving analysis that says a $150m booster deserves a $150m package comes down by 10% across the board. (and the circular argument that a $150m package deserves a $150m booster)Then , if we can begin to iterate we can reach the regime of $50m packages and $75m boosters, or better...)