I use a Superclamp with a short bar. I don't think those manfrotto speed clamps grip as well, and I wouldn't have anything sticking out nearly as far as the OP showed it. Weight at a Distance = Torque
Whatever your setup is, you want a factor of safety of 10... meaning you could reliably hang something 10 times as heavy as your mics on there without failure. If you don't think it would pass that test you shouldn't dangle it out over other people's heads.
The other thing to consider is that a superclamp will resist rotation much more if you clamp it one direction than the other. It's hard for me to explain it, but it's kind of like an oil filter wrench, one way it bites in solid, the other way it slips. Anyone who took a "Statics" class in college will probably remember the classic brake-shoe problem where the moment increases clamping pressure.
A windtech is fine if you are putting your mics directly above the bar... there is no torque.