[elicious]

Sticking with the hardware angle for just a moment,
i unashamedly copy Allen Sides, who when recording Streisand and many others,
uses (when needed!) an original DBX 160,
where he would manually ride the gain using the output knob;
which he reconfirmed recently at Namm saying that,
or an LA2A (no more than 2-3 db), is still his preferred method.

So besides compression, consider using old-school analog style gain riding;
that's a great way to achieve level density without changing the character, or coloration of your vocalist.

And since you mentioned zeroing in on plug-ins,
we've been through just about every one out there,
and find the most effective is by TBProAudio,called the GainRider2.
(although there is an issue with it releasing the buffer).
b.o.l,
e
for the record studios