Tech,
You say you'd remove the top but leave the side glass in the doors which leads to leaving the upper door frames (that surround and support the side window channels) and the hinge pillar for the rear doors in place, but your '17 T picture is a Phaeton using side curtains. Are you thinking just cutting away a BIG sunroof out of the top, leaving the structure that the top of the doors fits into, or is your plan to have it look more like a Phaeton (maybe a third seat in the former bed area?) for total top down open air cruising? Maybe you have an idea for window supports and filler pieces that you didn't describe? Just trying to visualize this grand daughter dream machine with fold down top....