Initially, no modifications were made to the box. Over time, the following modifications were made:
Drill four holes (vertically) in the bottom of the box (two on each side) to allow for drainage of any water that might find its way into the box. The boxes are reasonably proof against rain when closed, but cooking in the rain or a Scout leaving the box open can result in enough water to justify the holes.
Drill a few holes (horizontally) just below the top of the box at the front and back, from the inside out. These should open under the overhanging 'lip' at the top of the box so no rain can enter directly. These (combined with the holes in the bottom of the box) provide for air circulation to allow any remaining water in the boxes to dry.
(optional but recommended) Install a check strap to prevent the lid of the box from opening too far. These were custom made from 1/16" stainless braided wire and crimp fittings, and installed with stainless hardware.