"So can you save a light so that it'll act like a parented prop?"

Yes you can. Parent the light to the prop, then parent the prop to a figure, then save the light to a Lights pallet using "Select Subset" to only include the light you want. The parenting will remain intact in the lt2.

Now for the bad news. The light will only parent to mask_1 (or what ever the name was). You will now have to load another figure (in the same scene), parent another prop to it, parent another light to that prop, than save that light as another lt2, and so on. Because the light was saved as a lt2 (light) file, when you apply it it will turn the other lights in the scene off. IsaoShi said that "In recent versions of Poser you can add lights to a scene without losing those already present..." but many of us still use P6, or even P4.

Yet another way to go would be to have the end user create a new light, then use a pz2 (pose) file to smartparent the light, and set its color and intensity. But you would still need a different pz2 file corresponding to each mask_#.

So I still think that putting the lights in separate pp2 files is probably the best way to go, and it has the advantage that the lights could be stored in the same pallet as the prop. If you don't feel comfortable doing this yourself, I would be happy to do it for you. My fee would be to keep a copy of the mask prop.