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.