that would have to be strong velcro.
way back (2 years ago)..when I had a dual 10" box I used a large bungee and hooked to the two D clips next to the package tray. Somehow, I had just enough force on it to keep it from ever moving. But before that my box would bang against my side panels of the hatch and crack them up pretty badly.
Another idea is to take out yoru package tray and secure "L" brackets to it and bend to the proper angle to attach to the back of your box. Once you get it all screwed together right you should be able to stick the package tray back on without being able to see much of the brackets you used.
way back (2 years ago)..when I had a dual 10" box I used a large bungee and hooked to the two D clips next to the package tray. Somehow, I had just enough force on it to keep it from ever moving. But before that my box would bang against my side panels of the hatch and crack them up pretty badly.
Another idea is to take out yoru package tray and secure "L" brackets to it and bend to the proper angle to attach to the back of your box. Once you get it all screwed together right you should be able to stick the package tray back on without being able to see much of the brackets you used.