Mr. Schludwiller, our unit mounts to the vetical face of the frame rail which by itself, is not enough. To properly handle the forces that would twist the bumper down under load, we attach the receiver hitch to the horizontal face of the crossmember where the now removed spare tire once sat. This triangulation of the mounts is extremely rigid, and has worked well in testing. Regarding the use of more of the frame rails surface area, we have found that there is a backing plate bracket on the model that comes equipped with the factory receiver hitch option. The plate doesn't allow the mounting bracket to slide inside the frame rail without some cutting/grinding. On this bumper, we are completely confident of our mounting system's integrity. I'll try to post some photos of it here ASAP. For more specific questions, you can also call me direct at 800-345-3305 -Steve.