Have you done any NPAs? Unless you are coupled to an FMS VNAV path, being 100ft below on an NPA is no big deal, and in fact is a good idea especially with low cloud but good vis, because it allows you to get Visual during the level-off at the MDA while still being just below the on-slope PAPI. The only requirement is not be below any limiting steps during the approach.
What the? You can't be serious.