I got locked in for a while, what if it was a real lock in.

Hey OP........

Short of jumping from an escape window OR being able to reach folding handle from an open window there is NOT much you can do except holler....LOUD

With the handle folded closed over the door, the handle attachment is right at the opening edge of door so even pushing/shoving/kicking door will probably not dislodge the handle.

Next time you are outside your rig, close the door, fold handle across door and then try to open it.......doubt if you can without lifting up on handle.