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:
Tony Finch – blog
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;
};