I think you should stop overthinking stuff and stop reading the internet. Seriously. When I took a physically agility test to become a full-time city firefighter, I was smack in the middle of a Smolov cycle. It never crossed my mind to stop for the agility test, despite being physically beat up and no where near 100%. I did get hired, out of 1800 applicants.
All I'm trying to say is... all of this "CNS Fatigue," macros, counting calories, fat gain, WHAT DO I DO!? talk should stop-- just be a man about it. Seriously. Train for the test, eat well, get your sleep-- and if you're REALLY worried about, take a few days rest before the test. Done. Stop pouring so much energy into thinking about it.