1994; 6 cyl.; auto; 147k miles... I take my father in law to the grocery store and doctors office in my truck and he has asked if I can install a grab bar inside the cab over the door to help him get in and out. The headliner in my cab is fabric wrapped and not stout enough to have someone pulling on a grab bar fastened to it. Are there two layers of steel in the ceiling (like my old '80 F100) that I can run screws into to hold this grab bar? I don't want to go thru the roof of the truck with screws. Thanks.