Hey Scott,
To be honest, all the script does is draw a 'ring' of a certain thickness to the size needed. The width and height parameters followed the standard boundary box, so you just stretch it to shape in 2d and 3d. It was a dumb 3d only object that was put on a layer that was turned off when on plan.
I kept the original window/door/opening in place and manually adjusted the trim if the opening moved or changed size.
Just a thought, but have you tried the 'Custom Closure' setting instead of the turn skins? If you set the reveal depth to 0, the cavity closer actually does turn the skin all the way across and does this on the outside of the opening. Maybe this will do what you need instead?