I, for one, hope that the way custom maps are organized is completely different in Plazma Burst 3. As a primarily singleplayer custom map maker, I have tons of maps for each level in my custom campaigns and only the first and final get any votes. This hurts my ranking.
Regardless of the implementation, I hope that PB3 has a way to combine your singleplayer levels into one custom campaign which can be ranked as a whole instead of the current system which works best for multiplayer.