For me the biggest safety concern is a 32-Ft Class C on an E-450; which is likely near the chassis max load rating, making it fairly dangerous in itself. Beyond that, towing a Wrangler (with good brakes) that pulls a couple of jet skis (assuming also with good brakes) doesn’t seem much different than pulling a 6,000-pound pickup or similar vehicle. Other than extra length concerns, I don’t believe it would be inherently unstable.
I think visually it looks a lot more dangerous, but in this case I’d bet it was very stable because Jeeps have very short rear overhangs, and boat trailers are also normally very stable when set up correctly. By comparison, I would never attempt towing a boat or car behind a 5er or camping trailer.
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