Piano hinges look nice hidden or on top. Theres more 'hinge', so its strong, but it also depends on what size you get. For your rear deck, you could use piano hinge or even 2-3 door style hinges. As for cutting out, jig saw works well, especially if you are carpeting. I would use carboard cutouts and lay them on to see what layout works best. Be aware of the space underneath and if your hatch placement allows clear access.