My wife was thoughtful enough to write down a mile-marker. (Would have saved myself some walking if I'd just spent a second to record my GPS position in the first place.)
(I didn't think I would do this, for one thing I hate to blow almost 9 gallons on travel to recover an item intended to save some unknown quantity of gas, but later on I realized that a) I really like the shade in the back seat from the Kamm, at least for some angles, and b) 9 gal is actually not a large fraction of the gas that the modding kit as a whole (is supposed to) save in 1 year. So...)
It took a while, but I in fact found it and brought it back.
Road-side engineering: I've just un-bent and restored 1 of 2 of the anchor magnets here. I brought my drill and rivets, and 2 new hinges:
(By the way, the white car in the background is presumably doing 75MPH. Mind boggled by Galaxy S4 shutter speed, at least in broad daylight. 1/2000 of a second, or so?)
Addition of a tie-down strap makes this orders of magnitude more secure. I think the duct tape around the C-pillar edges is also a big deal. Plenty of duct tape in other places out of paranoia / aerodynamic-lust.
This got me home without a hitch, through some windy conditions that I think might have been as bad or worse than the conditions that broke it. So I just need to engineer this into something more usable (partially described above).
I saved one piece from the Kamm-to-AHB-window for kicks, but as you know that shattered. Actually I think it was made from PETG, and the black lid was pushing it past glass-transition temperature in sunlight and it had already become rather concave, and so was well on its way to self-destruction anyways.
Oh, and, I drove for mileage on this one. 54 MPG over 470 miles (estimated), probably centered at about 65 MPH. P&G / EOC as usual. This trip ends up with a lot of I-15 mileage on it, which me and my family have noticed has almost magical effects on MPG.