Following my previous entry, I emailed <bind-suggest@isc.org> to suggest an improvement which would allow me to do what I want directly, without fiddling with features that aren’t quite the right thing. I got a reply from Mark Andrews who says that bind-9.4.0 will do what I want, according to this changelog entry:

  1798. [func] The server syntax has been extended to support a
               range of servers.  [RT #11132]

This will allow me to say the following, which is exactly what I want.

  server 192.168.0.0/16 {
    bogus yes;
  };