Just use some angle iron and weld some easy mounts up. two piece of angle iron a mount. Two holes in one piece, the other cut to straddle the tube in the middle of the piece. Make the holes elongated so you have adjustment room. Make one for front and back, bamb, no more screwing with mounts that don't really do much adjusting. And if you find a bed frame on the curb, free angle iron!!!! You can make about 50 sets of mounts with one bed frame.