He needed it in a hurry, so other things this morning got put on hold to knock up a suitable piece of equipment for him.
Two issues were strength and lightness. Here's the result. 360mm long.
Ballmount and camera attach to the right hand end in this photo. Tube is 22.2mm stainless and both ends are machined aluminium...

Ballmount screws onto this 3/8UNC thread, which is actually the end of a socket head cap screw that runs the length of the aluminium shaft (about 60mm). The aluminium is threaded so the bolt could be locktited in...

Both aluminium ends are a tap in fit retained with a button head. The Ball mount is locked in place with the set screw you can see in this pic. You'll notice the 'meniscus' where the flat disc meets becomes a shaft that runs inside the stainless. This removes the stress point that would exist if there was a sharp change from one to the other.

Handle was supplied. The aluminium end here has flats milled on it for the handle and the bolt. Hole in top is for a safety line to the operator or aircraft. I thought it would be a good idea to enable the operator to use both hands if need be so trotted down to the Oxygen Cycles
bicycle shop in McLaren Vale and purchased a set of 7/8 handgrips in matching blue. Sliced the ends of them off and super glued the pair in place to give a generous grip area...

Now in the post so hope he is happy with it. Nice to have the tools and experience to be able to create a good looking as well as strong solution for someone.