Flexible tent poles are placed into each socket...

...then bent around to the other side. The wooden pole down the center top adds support. If it's needed, some kind of ties can be fitted onto it to keep each flexible tentpole in its correct spot, but so far they seem to stay pretty well.

Just a note: A more rounded curve would probably be possible if one wanted the more typical bow top shape. It would just be necessary to angle the pole brackets slightly, and reshape the end walls.

We found a very simple futon and frame that just fits into the wagon. By day it's a couch, at night it folds out into a bed. Even with the bed pulled out, there's still space at the end of the wagon for a small shelf to hold Darren's stuff.