I should have thought of the #p thing.
(setf *show-lisp-errors-p* T)
hasn't shown any errors yet, while trying to access 5757
So it looks like I'll be trying out the TBNL debug feature you recommended.
I don't mind the orgy of setf. It reminds me of a .emacs :)
I know that Brian Mastenbrook used cl-trivial-configuration-parser for
cl-blog, but that was his way of doing it.