Well I got it back! Saw it mounted on a ratty van right across the street from where it was stolen from! Couldn't believe my eyes. I stopped to check it out and it was definitely mine. Same rust spots showing through the hammered black paint I had applied a few months earlier. It still had part of the mic stand I had mounted to it attached too.
Looks like the guy lives in it right there. It's in front of a low-rent apartment complex and next to a liquor store. The hood was up, windows were open and the side and rear doors were ajar. I assumed he was sleeping in it right then.
I went home and grabbed a pair of bolt cutters, a step stool, my tool belt, and a hammer... just in case things got sketchy. I drove back and nosed it up to his hood so he couldn't drive off. Had my wife stay in the car and record video. He rigged it to his roof rails with zipties and a U-bolt. The bolt cutters made quick work of that. I kept expecting him to come out with a bat but he never did.
This all happened yesterday and we drove past it today and there was this tweaker dude sweeping the sidewalk out in front of the van. My wife was like, "That's him!" Apparently she saw him slowly ride by on his bike, staring at me taking off the rack. So he knows who I am, and I know who who he is. Hopefully that was the end of it.