Inspired by Langy's video of a few weeks ago with the under boom mount
Could not find a suitable clamp to go on the boom extension tubes despite much googling. Did however see lots of c-shapes with grub screw to attach stage lighting to standard 50mm tubes in scaffold, so thought I'd duplicate it just smaller.
So cast up a c-shape with resin and glass, added a bit of sectioned carbon tube to stop the rocking (longitudinally) and it is rock solid

Now for some wind. Sigh...
Maybe whilst waiting for wind I can clean up the birdsh!t looking glue job on the bottom tube but hey more material is stronger right