I have acquired new gravel shield hardware to replace the old on our 19' Scamp. The new hardware came with the proper rivets as well as washers. I have replaced the hardware on the Gravel Shield using the washers over the rivets on the opposite side of the fiberglass panel as the hardware. I am now about to replace the fittings above and below the window on the Scamp it's self. My question is, are the washers really necessary on rivets inside of the camper? I just want to avoid haveing to deal with removing the rat fur and insulation to get at them. Should a bit of butyl sealant be used around the rivets as well?