https://www.youtube.com/watch?v=qEWtBV9I0U4&t=136s
Also shows how speed effects trailer stability.
https://www.youtube.com/watch?v=PFzrWHTG5e8
Which is why longer trailers are probably harder to tow.
One from U-Haul showing proper tongue weight.
https://www.youtube.com/watch?v=4jk9H5AB4lM