Thank you all for your help!
I was away for a few days, so today I tried it again: A few sharp raps per Mike's suggestion, kind of hard because of limited space, then I tightened the bolt as far as I had loosened it before, a couple more raps and the little bugger finally came out.
If that didn't work, I had the torch ready....
The fronts were so much easier with much better access to those bolts.