[George C]

We've had good success the past few years by using a T nut on the inside of the bumper board. To prevent them from falling/being pushed out, we fasten a short piece of 1/8 x 3/4 flat aluminum over the T nut using #4 x 3/4 wood screws on the inside of the bumper board. The aluminum flat has a clearance hole through it. A threaded post screws into that. The post has a 3/32 hole in the other end for a hairpin cotter pin (aka R pin). The post fits through a hole in the frame or bracket installed for the job. A bit of Loctite stops the post from loosening off but allows for some adjustment in and out.