If this is only something you need for the development stage, and don't need backwards navigation at that point (or can enable the TOC for quick development navigation)... How about instead of hiding certain slides, setting the "on enter" action to "go to next slide." Theoretically this should skip the slides without removing them from the published file, which would make the variable correspond to the filmstrip numbers.
It might be a bit harder to keep track of which slides you're skipping (instead of just looking for hidden slides), but you could add some sort of indicator caption on each skipped slide. Or you could probably use F9 to see which slides are currently set to "go to next slide" upon entering.