This may sound stupid, but has anyone thought or tried to make a "pass-through" in the dash pad, out of to two or more dash vents (say from a TJ/XJ dash), from the windshield vents? There would need to be a closure of some type between the windshield and dash (so one or the other could be used, rather than constantly split forward and up).
Obviously this is simplified theory; space is an issue, custom work isn't as much. But what if you were to run 1 or 1 1/2 inch ducting through the dash pad (i.e. hollow out the dash pad to allow for horizontal relocation of the vents)?