Cassones RV in Mesa Arizona had a Winne Travato on the lot with a slick two panel side mount system using German gas shocks to hold and stabilize in the up and down position. The mounting was done with piano hinge. This appears in a youtube video by AZ expert. I'm damned if I can find the video...
Steel tube roof racks are not really super custom but they are one off. A lot of welders will build them. I put a full roof rack on a new 1977 GMC step van. The key as I saw it was to dampen shock. I was able to find rubber cone isolators from Wefco rubber products in Santa Monica. I put these...