I am building a new box which is the exact height dimension as the space between the floor of the trunk and a metal brace that runs under my rear deck. Would it be better to provide 1/2 inch of clearance so that the vibrating box does not transfer energy to the rear deck, or would building the box so that it fits very tightly under there be better, both to hold the box and to perhaps provide pressure to this brace for added damping in my trunk?