Can't figure out what I'm seeing

[Bugguy]

I have no idea what is being towed on the interstate in Tennessee. I've seen a lot of odd devices - carnival rides, etc. - but I'm stumped. I thought maybe a dunk tank from a fair, but no top opening or chair. It appears to be an observation chamber of some type, but for what? Google images drew a blank. I figure someone in the Forum will have seen one in their wanderings and can clear the mystery for me. Thanks!

 

[LizzieMaine]

Maybe part of the central column of a disassembled merry go round.