I can dig up more pictures. but the measurements are easy, it just goes rail to rail (inside) with about 1/4 inch of slop (1/8 inch each side) The reason you have to remove the bumper is because it slides in under the tie down bracket bolts. you have to slide it in from the front, the center bolts are actually in the center of the spring hanger brackets. The braces are welded to the plate about 2 inches in on each side so they do not hit the frame rails. There is about 1 inch of space in the front and back. not enough to get your hands through to bolt the bumper back on, this is why I have to do that from the top with the grill out.
you could use thinner plate, I had this plate already so the only thing I bought was the square tube. attached is pic from the front with bumper on. I made a thread here on ss about this, I will search to see if I can find it before searching through my pics.