I just got the Dual kid hauler version of that trailer, Except with spoke wheels. Master cycle was the name on the covers.
I have stripped it down to the bottom frame, will look just like yours when finished.
$15 at a flea mkt btw,
Mine had a lot more wear and tear than this one but was complete and serviceable.
Unknown age,
It will get new tires, n tubes n rim tape.....
The rims are steel, the tires weigh a lot..
I may stitch up some aluminum rims..
The hubs roll nice but got some play, I'll pop the jesus clips and see if I can adjust the bearings.