I wonder if the SWICK would have worked better if all plants were in the same size pot. That might help keep them all at the same level. Then the depth of the perlite/pumice/whatever, and the depth of water could be adjusted for correct pot saturation.
As long as the pots are sitting on the surface the water level is at the same point for all of them. They can be any size or shape. The perlite base shouldn't shift that much that it would be of significance. You can always add more perlite beneath an individual pot to mound it up higher if you so desired. Ooooo, I had some interesting things go through my head there.