Hello Tillie! I hope you and Valentino are both doing well today.

Rocket had SRT in August of 2019, and is doing pretty well, all things considered. Like Wendy said, ECID -- and especially after SRT. I see you're testing frequently -- you probably don't need to test quite so much, especially when he's in the 300s+, but I definitely understand, being just a week out from his procedure. At some point you'll be able to get a feel for how fast he can drop (with Rocket, it's around 50pts / hr max, unless he's sick, which has been ~65 pts /hr). Anyway my two cents was going to be that they can fluctuate a lot after SRT, but you're testing, so you have that covered.
(edit: was just informed you're using the Libre -- d'oh!

)
As for Rocket, well, I have to make frequent dose adjustments because he is incredibly bouncy. There was a point where I was trying to follow TR, but it just doesn't work for Rocket unfortunately. Only mentioning this because I don't want anyone to look at Rocket's spreadsheet for dosing advice, though feel free just to see what another acro kitty's chart looks like of course.
For the past few months he's been dealing with what we think is IBD, so he started on Budesonide a week ago -- which adds another variable to the mix. So this week has been... interesting. But he's happy, eating, and getting... occasional blues and greens. It can be challenging but you're doing a fantastic job. Hugs to you both.
Oh! On the cheese issue -- cheese is low-carb, so it
should be fine. Rocket gets some occasional cream cheese (just a lick or two, not a bowlful LOL) and he loves that too.