I'v run into the same problems - the Crux is not so easy to build a lightweight, safe, stable and yet simple windscreen. Maybe the simplest, lightest and safest option is to use a modified MSR Windpro stove and a perforated BMW Ti foil windscreen. My solution for the Crux is safe, relatively stable, effective and in my wiew simple. The crux has a spring-loaded sliding aluminum cylinder to lock the burner in upright position. It can be used to support a light aluminum baseplate. I used 0,5mm round aluminium plate slightly larger than my pot. (evernew, 0,9l)I made a cutout slot large enough to fit the inner tubing of the crux stem - very much like the link to Jim Woods windscreen in the last post. The outer edge of the plate is bent upwards, to make a small rim of 1-2 mm height. To provide ventilation and reduce weight, I've made lots of perforations. All edges is rounded and polished so I do not ruin lightweight nylon gear. A BMW Ti foil is cut to fit the pot, and is kept in place with a pair of paperclips. Heat from the burner is shielded from the canister. The metal walls shields wind and conserves heat for efficient cooking. During use, especially on full heat output, the foil can sometimes glow red-hot. This seems to be of no significance and it cools off in few seconds after the heat is shut off. It is not "bombproof", in my opinion, only Trangia cookers has decent bombproof windshielding. They are too heavy for my use. I wish I knew how to post pictures, then I could write a DIY description.
As with all hommade windscreens, the disclaimer should read something like, this works for me, try it yourself at your own risk.