I once spent a couple hours inside a Cobra trailer after one of the
rods became disconnected from the handle inside the square tube.
Luckily, the glider was assembled. Unluckily it was during a contest
at California City, so it was brutally hot in there.

If I recall correctly, the two rods that come out the ends of the
square tube are joined in the center by a small cam that is operated
by the handle. If you remove the handle, then you can slide the three
(two in your case) joined parts out one end.

One of the "no-no"s in using the Cobra trailer is to operate the
locking handle while the side latches are open. And you should never
unlatch the sides if the handle is in the locked position. This is
likely why your rod came loose - as it was jammed at the end due to
the back of the trailer lifting a little due to the latches being
open.

Good luck.