Though not about Barth but it shows what the thinking was at the time....

Modern Metals, Volume 26, Page 94, 1970:

All aluminum unitized construction is the basis for a new concept in motorhome design by the Ferber Coach Co., Milwaukee, Wis. The entire body shell of the vehicle, including formed aluminum structural members, braces and body panels, is welded together to form an integral unit. The panels forming the sides, base, and top of the body are clamped in special production fixtures and the interior braces are welded in place. These sub-assemblies are then tack-welded together prior to final welding with straight edges to insure proper alignment. Each body seam is then MIG-welded and ground smooth. All body panels are formed from 1/8- in. thick 3000 alloy sheet, supplied by the Earle M. Jorgensen Co., service center in Skokie, Ill. Hinged doors allow access to water, butane and fuel tanks and weatherproof luggage or equipment storage. An aluminum molding along the center of the body encloses the wiring, and is removable for easy access. Two body styles are built in models 27 and 22-ft. long. Both are 8-ft wide and slightly under 10 ft high. The 27-ft model has a sliding rear patio door and a reinforced aluminum patio. The coaches are marketed as complete luxury motorhomes for travel, sales offices, traveling display showrooms, and field offices, with completely furnished interiors, with custom interiors to owner’s specifications, or as unfinished shells.

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