Terrible luck indeed. I have to ask, how often are you playing the 20th and 21st frets of the A and D strings? I realize the issue is getting an instrument without any problems, but realistically does this actually hinder your playing in anyway whatsoever? How often do you fret without plucking? Does it happen with hammer ons? Do you do a lot of tapping?
It just seems to me like what you want is a totally custom bass from a high end luthier and not a production instrument. Maybe I am off base though. I don't mean to offend btw, it just seems like a lot of hassle you have gone through for pretty miniscule issues.
I didn't catch it the first time around but what issues did you have with the electronics of a passive P?
FWIW, I happen to like very low action on my basses and my plek'd JB pretty much plays like a custom bass from a high-end luthier. For a production instrument, the US G&Ls can pretty well hold their own against whatever custom you want to compare them to.