What I did was get some 1/2" molding (half round). Paint it black to match the removable floor (the thing that covers the spare). Get a box that will hold your stuff and Attach the molding to the removable floor so that it holds the box in place (use very tiny screws (drill a hole through the floor and drill holes into the molding so it does not split). You can do some pretty rugged corners and the box will not come out of the molding, and you can still remove the box and put in groceries (or what have you). Also works with laptop cases. If the box is very heavy, you may have to put some velcro dots under the floor to secure it to the car proper.
Steeda SRI w/CAI intake. Trubendz SS 2.5" . FR Susp/Struts. Tune by Tom (FocusPower). Rota Grids. SAP rear spoiler. Custom front air dam, rocker panel bits and Rear valance.
Last of the Hatches #28