I know one thing. If I was hauling that aerial lift around on any trailer I would have something over the top to hold the platform down, the way this thing is rigged now its only got chains fore and aft from the bottom of the lifts' frame to the trailer, on a bouncy road I wouldn't trust the platform to not jump up and down. Anyone here moved these things before and should it have some additional restraints?
"A lot of the farmers I used to know would use military surplus D ring hitch high capacity trailers... all were single axle."
But those trailers are designed to be drug at relatively slow speeds and across battlefields. Most older Mil vehicles were not designed to travel at over 55 mph for very long, if they went that fast. A convoy moves at 45 to 50 mph normally IIRC.