Played some with the search terms and found something that might fit with the VRAM and unconventional connector on board that interface card for the setup. For a pricey projection unit for the luggable, the oddball connector choice makes a lot of sense.

Does the card draw Power & ground connections from the external connector? That would fit in with the draconian Power budgeting of the Portable. When the projection panel wasn't plugged in the Video Card would be comatose in its powered down state, drawing no power from the Luggable.