Where is the crack in your sidewall? I see many fifth wheels that have an expansion joint below the bedroom slide where the sidewall is very narrow on the overhang. I have a 2006 Jayco Designer 31RLTS that developed several very small (spidery) cracks in the sidewall just below the bottom left corner of the bedroom slide. I have looked at other Designers of the same model and vintage and noted similar cracks. I contacted Jayco and was told that this does not mean the frame or welds have failed. There is a certain amount of flexing and twisting in moving a fifth wheel down the road. I am sure that if you measured the space between the front of your pin box and a reference point on the front cap of your RV you would find movement between being hooked and unhooked. Where is this movement manifest in the coach of your fifth wheel? Perhaps in all the contacts between the various panels and openings. Hopefully this movement is accounted for in the design of the coach. Consequently I just covered my spidery cracks with a piece of trim cut from a plastic venetian blind. Now that I don't see it it doesn't bother me as much.
