So it seems that I was about a minute away from a save point. Well, actually I was less than a minute from a warp back to my ship, which is a save point. Anyway. Warped and saved.
Then decided to play a couple of multiplayer games online. Just played against random people, and on my first game the host quit. On the second game, however, I came second. Which is pretty good, I thought. The trick seems to be to stay in morph ball form and drop bombs constantly.