It would be super cool to use the moon to circularize the orbit. But the orbit you'd get wouldn't be super useful, probably. I wonder about stability as well. And the practicality of achieving the velocity to reach that high, and aiming that precisely. It would be really cool to see some analysis of that.

Another out-there idea would be to shoot things at a space station that had a giant catcher's mitt or something. Would it be possible to design a decelerator that would work? And to hit it precisely with a dumb projectile from the ground?

A third possibility would be to recover and reuse the rocket engines en masse. Not sure how it could be done in a way that was cost effective though.