A properly loaded trailer should be safe at speed, but many trailers aren't properly loaded and this can happen even at moderate speeds:
https://www.youtube.com/watch?featur...&v=TDsfhYzUKDI
The tongue weight on my Renault is only 75kg so there's not a lot of leeway. My suspension drops only 9mm at this tongue load. If I followed U-Haul's advice of 1" sag I'd need to have 200kg on the ball
