I finally found Bokke Alberds' death record. As usual, it was a matter of paring back some cruft I shouldn't have had in the entry in the first place. I'd taken the default surname, when he didn't have one (his daughter used one, but he didn't use one). And there were some spelling variations -- I'd picked the t in Alberts when I should have used a d for Alberds.
But there he is, dead at 55. Here's the real bummer:
Ouders onbekend, geb.plaats niet vermeld
That's bad, and allefriezen confirms it.
Roughly: "Parents unknown, birth place not written down."
There's still hope of finding more information, but the flame of it is guttering.