I'm sure you know more about the limits of the air-cooled VW than I do. I simply meant to say in my original post that towing something that large seemed like a mis-match, that it didn't seem like it would work very well. The source article said the trailers were built to promote the firm's line of trailers and only two were known to have been built. They didn't sell very well. Seems like people who know the limits of their VW's avoided them.
I understand the limits of the vehicles I've owned. Decades of offroad camping with Willys Wagons, Wagoneers, Trooper, and the Outback I bought new in 1999,
shown working pretty hard in my photos above. (And in another post following that one) All of them stock. Never put a scratch in any of them (well except underneath the Jeeps, no harm done) and always made it home on Sunday evening, never been towed out of anything. I seem to know their limits.
Subarus are known for blown head gaskets when the owner doesn't understand they can't be run full throttle until warmed up. My head gaskets are still original at 22 years old. Have you kept a VW in service that long without any repairs? Why did it need modifying?
An old photo: