That kind of exception is one of the main areas I think major dists
fail.  Making it so absolutely difficult to insert administratively
know requirements at 'odd' points in the boot order.  When I last used
Debian it was easy with that S## / K## linking system.  Arch is
another dist that has a way of doing that, except it's based in a core
config file.  I like Debian's method more because then you can use
shell scripts to easily slice/dice/add things at given points.  Arch
is more than sufficient for normal tasks though.