The below images are from the Popular Mechanics magazine of June 1958. They show some photos of the popular Malibu Outrigger
It is hard to know how many of these were built, but it seems they were very popular for awhile. Later on the beach catamaran craze took over and these boats were largely forgotten. It is probable that these boats built with plywood but before the advent of epoxy resins would have had limited lifespans, and eventually they all rotted away. The little I know about this boat was that it went fast but did not point upwind very well. As to why this was the case, my best guess would be a sail plan that was had a low aspect ratio, having no jib, together combined with a board that was probably too small for the boat.
Notice that the rig, though large and powerful lacks a jib. When I was sailing a catamaran years ago, the hobie cats with a jib would always point higher than my boat without a jib. Thus my guess is that it is these three features that resulted in relatively poor upwind performance, as opposed to the geometry of having one large hull and one small hull. The daggerboard that can break on grounding maybe an issue, a pivoting centerboard may be preferable.
The Malibu Outrigger sailing manual is still available in pdf format. The manual is here; LINK.
The Popular Mechanics page on building the Mailbu Outrigger can be accessed online by following this LINK
Plans are now available in pdf format, approx 1mb each file size, thanks to Robert Van Putten for sending them
Plan 1 LINK
Plan 1 LINK