Totally know what you mean about the floaters getting air and starting mold. I had a whole jar turn into a science project last fall because I got lazy and skipped the weight. The top layer was just this nasty white and green fuzz, and the whole thing smelled off. After that mess, I never try to ferment without something keeping everything under the brine.
Yeah, missing a weight can totally ruin a batch. It lets the veggies float up and get exposed to air, which is where mold starts. I've had that happen before, and it's such a waste of good cabbage. What kind of weights do you use, or do you have a backup method?