Hi Henry. Good to hear from you again. Any good hikes this summer?
One thing I did when I was in the Japan Alps this summer was to fit my single hiking pole up against the end of the cross strut pole, right at the apex of my Rainbow, by the entrance. You can see it here in the second photo. It really made a big difference in shoring up the tent laterally and I think that if you could provide grommets at both ends of strut pole, allowing you to use two hiking poles, as with your Squall 2 and Virga 2, the Rainbow and Double Rainbow could really handle some strong wind. The hiking pole on my configuration never got in the way and helped prevent the top of the ridge pole from swaying foreward and backward.
The guyline loops that you installed, Henry, have been a lifesaver for stabilizing the tent longitudinally. Martin originally contacted me for more information about them. My two suggestions are that they be sewed with more reinforcement, and take advantage of the ridgepole itself in their function along the ridge seam, instead of simply being sewed to the outer ridge seam fabric. I would suggest a "U" formed single piece of grosgrain ribbon that runs around the pole and thereby pulls the pole itself when in tension.
I'm still uncertain about whether the guylines that would run from these guyline loops should pull in a single line along the axis of the ridge pole (as I've done here), or to two sides, as a "V" configuration, that would stabilize the tent at four points rather than just two. I tried out the second configuration here at home and the tent holds well at those four points, but, like the first configuration, the top of the ridge pole still oscillates badly when pushed (which is what I think is happening in Martin's photo).
Martin did send me some other photos of several earlier trips he took with his Double Rainbow in the Swiss Alps this summer. In all those photos he had pitched the tent correctly, as per your instructions above, Henry. I think the "incorrect" pitch he resorted to in the photo above was in response to the high wind and trying to find a way to cope with the Rainbow's bad handling of the wind. After all, you want some kind of battening down of the doorway, and with the big opening at the bottom, inevitably there is going to be a lot of "sailing" of the door flaps. I had the same trouble with my Rainbow this summer. The doors just didn't handle wind very well. I guess in an above-treeline storm you want to get as much of the shelter fabric down to the ground as possible. Even Ryan lowers his tarps to cut their profile to the wind.
I'm very curious why you don't incorporate some of the door design ideas of the Cloudburst 2 for more stability on the Rainbows... Just seems a lot more versatile to me...