Keep in mind if your working on cars (or anything else that might catch fire), a combustible lid is not always a good idea, unless your ok with the place burning down... this is a common thread on the site, you can go to google and search "garage journal ceiling" and you should find some threads. Most guys go with thin tin (made for lids) or osb for a lid, if its not sheet rock.
If you trying to get away from having to lift it (sheet rock), you can rent a lift, they will do 15' if you get the right lift. I bought one, for less than the cost of renting.