I'd be worried that without a nut and a bolt, someone would try to steel it, especially, as I've been reading in the neighbor from Hell threads, someone who wants to get you in trouble for owning/driving it. Even with a clean bumper and a plate whose back is slathered in JB, I'd think it would be a simple matter to use a prybar to remove the plate pretty easily by liberating the paint to which it's adhered, damaging the plate in the bargain.
The rear mudflap mounting sounds good to me for most MVs, but what about a truck like the long wheelbase models (814, 820, etc.) where that would bury the plate and light too far back from the rear of the vehicle? I'd like to be able to throw four tiny holes into the rear skirt of a cargo bed, small enough to be trivially filled with a flux core welder, angle grinder, and a squirt of primer. Then, I can use four good, solid screws to hold it in place, like I don't even do on my car (just the top two). Then mount a length of something like 24 VDC rope light over the plate in a reflector to cast the light straight down, in the space occupied by the rear tailgate hinges' pivot point so there's no way to crush it. I think since a vehicle like a large military truck will spend an exceedingly breif amount of its life in the "fast lane" of any multi-lane highways, the plate chould be mounted on the dirver's side of the vehicle.