Aluminum drawers in a box, same height as wheel humps, drilled to bolt to factory seat and tie-down threaded holes. bolt tiedowns to the top. Allow for optional plywood deck to go all the way across. maybe a hi-lift mount on the side, it'll fit between the box and the fender.
Oh, how about a bracket that replaces the idler pulley on the 2.6 and fits up a York compressor and a belt tensioner? Or just a blank bracket with a centered shaft hole and base holes/slots to adjust alignment.