Thanks Rick. That part and the hinge, all I will need to find is a lightweight pole of some sort.
I am guessing that the lightest pole I can find would be best, to minimize any stress to the crossbar, particularly when dropped off the rear as you pointed out. That is why I will try to avoid an extendable. I found carbon fiber tubing, but that stuff is pricy!

I will post results once I do it.

Appreciate the tips!