Cool things with wheels since 2006
That trailer is a c.1950 Airfloat, built in Los Angeles. We have a 1955 model with a Slimp dolly, which is a rare wheeled gizmo that used to be very common but is extremely rare today.
I'm familiar with it, as I posted about and Airfloat and Slimp combo in 2017 https://justacarguy.blogspot.com/2017/06/a-rare-thing-slimp-dolly-that-was-part.html
Yup that's ours