I have a set of design plans for a four-drawer dresser that I'm going to modify to make into a five-drawer CD/DVD Storage cabinet. The drawers will be 3/4" plywood, 40"W x 18" x 6"D and I will use rabbet and dado joints. I am also going to use ball bearing full extension slides. I originally planned to use 1/4" hardboard or plywood bottoms with a 1/2" strip of 3/4" plywood turned sideways and glued across the width of the bottoms for support. Would that support prevent the drawer bottoms from sagging or should I use something thicker for the bottoms like 3/8" or even 1/2" plywood (without a support strip)?