How about a SpaceX fuel drive starship, with the upper stage nothing but fuel for the launch to orbit, and the lower stage separates and attaches to a moon bound upper stage, like a prefabbed habitat module, propels the habitat to the moon, the habitat has only enough fuel for a moon landing. Then the drive stage returns to Earth orbit for refueling or all the way to the chopsticks. The almost upper fuel stage will have already returned to Starbase after the separation? Or basically, two lower stages, one stacked atop the other, the one stage providing thrust to orbit, where the upper stage, which is also a booster, ditches the top fairing so it can be a fuel stage for Mars trip, or carry a habitat module to the moon, and then return to Starbase?