have you seen the pop tops they make for a landrover?? fold up to the side so you can stand inside?? kinda like vw bus but on its side vs front/back end...
looking at how our roofs are made.. you should think of a hinge down one side... then the ability to stand it up and canvas box for the other sides... when folded down have the top up above your head in all the dead/unused lots of headroom area... so no need for roof to be higher..
if my roof or headliner were screwed up id do it so fast.... i think you need to do it... then set it up like a old bus with canvas cots... or like newer ones with panel for foam matress.. i like cot idea as easy to fold/store... you could also build a roof rack into it..
