Not exactly stealthy, but one thing that I am working on is attaching SP-C4's to a hat brim so that I can tape from the sweet spot at any show and am not anchored to an official section or even to a convenient spot to clamp or put a stand. The best method that I've come up with so far is to rubber band the mics together right below the cap and then pivot out to a 90* angle, set the mics on the hat brim, and duct tape (or other wise affix) the wires to the hat above your ears to hold the whole thing in place. I then run the wires down the back of my shirt to my rig in a Lowepro fanny pack style camera bag. The mic configuration is very close to X-Y. The one thing that you have to worry about is the mic bodies rubbing on each other where they are rubberbanded together, so I put a piece of this athletic tape around each one at that spot.
It's not a stealth rig because I end up walking around with two large, shiny silver mics sitting on a hat brim, but it gives me complete mobility and both hands free. I'm considering getting an XL sized Kangol to see if it will fit overtop of a normal baseball hat for more stealthiness/anonymity. If so, I will just cut holes so that the caps stick out, and off I will go.