As you've already noted, go with the SuperClamp stud terminating in a 3/8" tip, then add a 3/8 > 5/8 adapter.
The Posi-Lok has a 5/8"-male on one end, 5/8"-female on the other. You'll screw the Posi-Lok 5/8"-female onto the superclamp stud + adapter (5/8" male termination).
Now you're left with a 5/8"-male thread, but the Bogen extension has a 5/8"-female stud end. This is getting trickier.
I haven't had to deal with all these adapters since mine's custom, but, I think this will do it, end-to-end (and there are probably alternative options, taboot):
SuperClamp >
standard stud 3/8"-male tip >
Bogen 3-8"-female | 5/8"-male adapter (
K&M alternative)
* >
jam nut (so you may align the Posi-Lok in the proper orientation) >
5/8"-female Posi-Lok | Posi-Lok 5/8"-male >
Atlas AD-5B 5/8"-female coupling barrel >
5/8"-male | 3/8"-female adapter >
3/8"-male Bogen double-ended 5/8"-male stud w/ 1/4" tip you can ignore (alternatively
3/8"-male threaded | 5/8"-male stud adapter >
Bogen extension w/ 5/8"-male stud & 3/8"-male threaded tip.
* I have at least 3 different lengths of 3/8"-female | 5/8"-male adapters: short, medium, long. The "medium" and "long" work just fine, but the "short" doesn't have enough threads to securely accommodate the jam nut + Posi-Lok. I
think the Bogen is the "medium" length. The K&M
might be the "long", but then again it might also be the short, or another "medium" variant...I'm not sure. To be safe, and to avoid shipping on piddly stuff like adapters if I've linked to the "short" version, you may want to consider getting both just in case.
Then, assuming you have a 5/8"-female threaded mic mount / stereo bar, you have at least two options to attach your mics to this contraption:
<1>
3/8"-female | 5/8"-male adapteror
<2>
Bogen Rapid Adapter (5/8"-female stud | 3/8"-female threaded tip) >
3/8"-female | 5/8"-male adapterPersonally, I like option <2> since it gives me quick-on and -off capability and it's what I normally use for running on my regular mic stand.
That'll work! But maybe there's an easier way to do this...
Allllll that said, and depending on the location / height of the PA stacks, you may not need the extension / Posi-Lok contraption. A SuperClamp +
Bogen right-angle extension arm or
Bogen heavy-duty flex-arm (if you have full-body or LD mics, trust me...you want the heavy-duty version) might do the trick. And remember: safety cable!