Fugitive that desk looks fantastic. The curved, bevelled front edge is killer.
I made a poor man's version of Monster's HOTAS mounts using a couple of inline clamps I bought, some 1"x1/4" aluminum flat bar, and 4 garage door track right angle mounting brackets and some wood scrap I had laying around.

The inline clamps are available from Amazon:
Bessey Inline clampMy shop skills aren't enviable, but these things work very well and clamp tight and solid with no play. They remove easily with just a flick of the clamp levers, and I can easily switch from center mount joystick to side mount. I found the key to keeping the brackets from sliding on the desk surface was to glue open cell foam pads on the inside of the bracket where it contacts the desk surface.