See if the "pre / post" toggle will help. You basically want to apply the effect first, then do the cropping second, right?

Open the effects window, and look at the mini-timeline in the bottom. Each effect there starts with a triangle pointing right, meaning the effect is applied after pan crop. Click the triangle so it is pointing left. Now the effect will be applied *before* the pan/crop.

I haven't tried this myself -- hope it works.

Tim L