reducing stress for international travel

We're about done with our tour here, and have gotten another tour to
another country far, far away... one that has a 30 day quarantine.
While we'll return to the US between tours, Meep can't due to the new
country's quarantine regs.

So, she'll have to be in a cattery for a few weeks, then in quarantine
for those 30 days.

Last time we did this journey/quarantine, she seriously stressed, and
was really a wreck at the other end. However, she was much younger and
hadn't yet figured out that cattery abandonment, and would stop
eating if she wasn't home.

She knows that we'll not abandon her now (or at least, she eats and is
less stressed when at a cattery), but still I want to to everything I
can to make this trip as stress-free as I can.

I'll be making an appointment for a full medical workup, as she will be
just turning 10 when the trip begins (poor thing, flying on her
birthday!). I also have a Feliway spray, her travel box is out, and it
gets sprayed every few days. I toss a few treats in there every once in
a while, and she enters readily, but doesn't stay.

Since she tends toward cystitis, I'm thinking it'll be a good idea to
send her to the cattery with a supply of the Royal Canin veterinary
formula she was on after her last attack, along with her glucosamine
supplement and perhaps the tube of supplemental dl-methionine, which I
use when her litterbox habits suggest she might be getting crystals.

D'ya think all this is necessary? What else can I do to lower her
stress level? Is there an additional supplement that she can take
during this difficult time (something powdered, she doesn't "do" pills)
that will help her relax?

She isn't called Meep "the travelcat" for nothing, but as she gets older
I worry more about her health. Any advice appreciated.

jmc