I use 1/4-20 stainless carriage bolts in whatever length needed. Love my TrailRax. Be sure to get the front deflector installed correctly or the squeak will drive you mad. LOL
I keep an assortment of 1/4-20 hardware in a small organizing bin box. This includes bolts, lifting rings (O-rings with a threaded stud), rubber clamps, etc. I put four or five stainless T-nuts in every slot on every bar, so I can screw anything I want in. Just yesterday I brought back a few hundred pounds of lumber, which I tied down to O-rings.
For recovery boards, I have four (plus one spare) 4.5-inch threaded studs, with a 1/4" nut close to one end. I screw them down into the T-nuts, then tighten them in with the 1/4" nuts. I drilled four holes near the corners of the recovery boards: they will be placed over the upright 4.5" threaded studs. Then I secure them with large fender washers and thumb screws. This way, I can lift the recovery boards off easily when I need them, and return them to the four threaded posts when through. From Amazon: rubber clamps for axes, wood saws, shovels etc., and stainless T-nuts.
