Securing hose bib to uneven cinder block wall
So what I did took a couple of weekends and the acquisition of new tools and skills, but I figured it out to my satisfaction.

I did Steps 1 and 2 from my checklist above.  For the spacer, I build a 3x5" box out of 3/8" plywood and scribed the edges to match the uneven cinder block.  I used a rotary rasp bit on my drill to “carve” the box edges to my scribe lines.  It took a couple of tries to get it to fit decently, but in the end it pushed out the flat box face away from the cinder block and just under the siding.  

I painted it with the same outdoor masonry paint that we used to paint the cinderblocks, and applied caulk along the edge.  Inside, I filled the gap between the block and the pipe with expanding spray foam.




Jack's answer is still a good one.  I just preferred not to punch a new hole in the wall.