I would have the large "lift-wing" attached to a SSTO spaceplane. There might be a problem hanging a fully-fueled rocket in the horizontal position, i.e. buckling. But I'm assuming for now that this problem could be fixed by using multiple explosive bolts evenly-spaced along the entire length of the rocket, hanging it from a very long mounting boom below the lift-wing. The lift-wing would be self-propelled rather than towed, and I think I would design it for absolute maximum lift -- a double bi-plane or tri-plane with three narrow fuselages, one in the center, and two at the wingtips to prevent wingtip twisting. Winglets would be needed on the front bi-plane wings to prevent tip vortices from reducing the lift of the rear wings.