PSIA does not advocate against zipper line skiing. It's one of many tactics one can use to ski the bumps. You will find higher level PSIA folks encouraging you to be ABLE to ski the bumps using other tactics and encourage you to TEACH those other tactics when INTRODUCING skiers to the bumps. There is consumer demand for learning zipper line bump skiing - see the instructors in Europe thread
. PSIA loves giving the student what they want.
As for suggestions, the main thing that PSIA looks for with other tactics is the ability to make turns. If you can make dynamic short radius turns, you're 90% of the way to performing any of the other non-zipper tactics in the bumps. If you can't, learn the desired movements on the groomed runs first. The other 10% of bump skiing is choosing the line, maintaining contact with the snow and staying centered over the skis. Those are things zipper line skiers should be able to do well anyway. Can you make constant radius turns regardless of where the bumps are? Start with small bumps or ski larger bumps slow and more across the fall line, then work your way up.
More efficient turns are not necessarily more fun turns. Zipper line turns are fun, but they're hard to do all day long. Having an easier way down in your toolkit will make you a better skier.