Here is a strange idea.

Picture a basic flatbed trailer. Add the left and right walls, hinged at
the bottom and outside of the floor to fold from the normal up and down
position to horizontal and beside the floor. Drive a fuselage onto each
side, secure them in jigs, winch the sides back to up and down like normal.
Wings secured in jigs between them. Front and back and top stationary with
smaller access doors.
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Jim in NC