You are in a business involving wires, circuits, and voltage. Anything that doesn't fit under the tonneau or in the cab with you faces exposure to cloudbursts, etc. I think a tall topper is really the best choice. If you do any cold-weather hauling of items for immediate setup upon arrival, a couple of cheap "lighter plug"-type electric 12V heaters back there to lower the temperature differential wouldn't be a bad idea. SMD electronic boards are very vulnerable to condensation when brought in from the cold. I learned that the hard way, shorting a desktop years ago. :doh: