So, I installed the Winfield Cross-brace stabilizers, and it was a remarkably quick and easy install, and so far (from just a quick shake test) the results seem excellent. Without the stabilizers there was a lot of side-to-side movement. With the stabilizers tightened I couldn't get any noticeable movement at all from a shake test.
Pictures in my mods album, and below: -
As you can see the braces cross from one leg to the other, providing excellent side-to-side stabilization. No drilling necessary, since they just clamp on to the outer leg tubes.
Tightening the stabilizers when setting up only takes a few seconds.
Top and bottom bracket install on left landing leg (no idea why I can't get any photos to come out portrait, despite the photo being portrait on phone and camera)
Upper mounting bracket install on right landing leg. The bracket just clamps to the landing leg surround with a custom U bracket, and a couple of nylock nuts. The top of the cross-brace then just attaches to the bracket with a bolt and nylock nut.
To install the lower mounting bracket you just remove the clip pin holding the foot in place, and replace it with a bolt that goes through the mounting bracket and through the holes in the leg (I was able to do this with the legs down). You then just attach the bottom end of the brace with a bolt and nylock nut.
To setup you just twist the two ends of the pole until you have an available hole lined up (the holes in the outer and inner legs are at different spacings so that you don't have to adjust the full distance between holes ever), put the clip pin through the leg, and then twist the two parts of the pole together until hand-tight. Repeat for the other brace.
To teardown you just reverse the process and loosen the brace until you can remove the clip-pin, store the clip pin, and retract the legs.
The next time you setup the holes should be already relatively lined up from last time, assuming the landing legs are extended a similar amount.
I'll report again on how well they work after our next trip in 2 weeks.