Brian
How about two presure shocks or a torcion spring to raise the top.and a cable real small gear driven shaft with cable on each back corner of bed. reversing a 12vdc mtr is nothing. Like an overhead door only the cables would come from the bottom up, not the top down. You could even put it all under the truck and just have the cables come thru the floor and attach to the top. I better stop before I confuse the issue. Your the engineer so ENGINEER