I'm not who sure where you can get them, but I have seen a yellow fiberglass adjustable pole.The only mod. is to put a handle on it and drill a hole in the threaded end so it can be attached to the cross bar.
One bad thing about the that type of pole is the surface finish breaks down in the sun and you start getting fiberglass in your hands.
OUCH! - reminds me of around 18 years ago walking along the beach as a young fella, and jammed a 2 inch long sliver of fibreglass from a surfboard underneath my toenail, it healed pretty good though.
But the scar I got from standing on the rusty 4 inch nail hanging off a plank off wood buried in the grass was a different story.
