Your problem really is that your batten pipe is rolling, so fix the problem, don't treat the symptom of your problem. I'm not an LD but it does seem to me that you could achieve that lighting angle without yoking the instruments out so far.
Assuming you really DO need to yoke out your instruments that much (because it occurs to me you may need the instrument slightly higher to achieve a preferred angle but the length of your soft goods prevents from just taking the batten higher, right?) and assuming you have the space on the D/S side of the batten to do so, you COULD hang & yoke out a few additional instruments as ballast opposite these ones. You probably don't need to hang instruments one-to-one; maybe one ballast for every two instrument - just to get the pipe to "roll" back closer to where it belongs.
The side arm stiffener doesn't NOT work, but it seems to me that it treats the symptom and not the problem? Balance your batten and you should be fine.
It seemed time the reason for roostering the fixtures was a border directly downstage of legs, which share this pipe with the fixtures, resulting in the fixtures being too close to the borders if not roostered.
@Jason M Wagner Two additional points to ponder: a; The longer the side arm the better. b; If you only tie the side arm to the lift line at one point; choose the upper most point, it has the best mechanical advantage and does most of the work.
I've seen end users go wild employing tie line in six, or more, places and / or lacing tie line around both the side arm and lift line from top to bottom; waste of time, effort and tie line. The top tie wins in terms of mechanical advantage, additional ties are for show and making yourself feel more important, somewhat akin to the high school kid with tiny, LOUD bells secreted on his LARGE and jangling collection of unused keys.