Ok so here’s the situation… I replace skylights for a living, and often do the interior work myself, whether it be a small piece of trim or drywall repair/replace. In this situation I have N existing skylight with a drywall “well, or shaft”. That size doesn’t exist Anymore, so I need to frame the opening in let’s just call it 4” on either side, to fit a standard size skylight. Once I do this I am essentially left with a 5 1/2 (2x6) x 4” bump in on each side.