How about Harlequins with a Phoenix Lord assaulting a flank? Tau can remove cover but I'd think that due to the Halequins' veil of tears there's a chance that not all supporting units will be able to draw LOS and fire over watch on the Harlequins. The Phoenix Lord can tank the shots that do come.
Thoughts?
If I'm not mistaken, LOS is generally not an issue for Tau.
"Any unit wishing to target them must roll 2d6x2. This is their spooting distance in inches. If the models are not within spotting range, they may not fire that turn."
So...while SMS doesn't need LOS to fire, you still have to be able to legally target a unit. VoT says nothing about Stealth/Shrouding/Night Fight/Cover/Blah, it specifically says "wishing to target". Based on that, I would argue (even as the Tau player) that if I dont get that 2d6x2 range, I can't even target to fire.
Now, admittedly, it's still a best case scenario for me because your max charge range is 12" so all I need is 6+ on 2d6 to see you with each unit, depending on how close you are to each unit.