You will need those rivets to come from the factory as there is a special length that we doubt your local jobber will have. The area is also machine screw and nylock nuts every few feet on newer models if you can reach that area from behind on your rig.
Removal is either a needle nose vise grip and pull the rivets out, or drill the heads and punch out (option 2) and then simply replace the existing rivet. You can also add one every now and then to tighten that area, though we are cautious on the amount added in the event you require a replacement rub rail later, thus no swiss cheese effect on the exterior edge there.
BCB