Seal the top with silicon but leave the bottom unsealed. This will let the moisture(condensation) out. I use nuts and bolts to secure it on, this lets me take it off and repair the bigger dents. Repaint the holes you drill before you bolt(or rivet,screw,,) it down.
Wayne in Hawaii
PYRO II, 77CJ5
Wayne in Hawaii
PYRO II, 77CJ5