We're planning some long trips in our 2009 Sonata Limited with three drivers and would like to create a sleeping area by lowering the rear seat and allowing the sleeper to extend their legs into the trunk. But some type of matress, pADDING, OR CUSHIONING IS NECESSARY TO smooth out the seat to trunk ridge or lip. Any suggestions? Any accessories? Pillows is obviously one possibility but something like a fitted foam cushion would be better.