You could make a good wedge type with a all thread rod and nut in the 5/8 ''x I' for about two dollars and some scrap steel , what ever you use store bought or home made you should wait for the tires to cool down or you will have to readjust the fit as the tires shrink . To stop the movement on a fifth wheel look in to the tripod at camping world or other vendors ,or again make your own for about twenty dollars for scrap steel and threated rod ,washers,bolts and welding rods or wire , I use chocks and three Try- pods One big one in front and two small ones on back bumper ,works for me stops all side to side or front to rear movement I also still use the wood blocks fore and aft . Ron Bissett in Metro Louisville KY (entry level for almost fifty years)