There will be no chrome on a tactical vehicle, and very little in the way of distinctive markings. The "FORD" & the logo would also be green. Everything would be the same color (body, frame, engine, driveshaft, interior)
As for the bumper numbers, the numbers on the passenger side front is the unit (on my M927 is XVIII ABN/43ADA), while the number on the drivers side front is the vehicle number (C-11 in my case, which stands for Battery C, Vehicle 11). These numbers are switched on the rear of the vehicle.
I think you have a good concept, and are off to a good start.