I kept it as simple as possible but there is more flexibility possible.
One is that you don’t have to keep exactly the same borders (this invisible line passing between the black and white stones ) as you can permute stones touching this boundary to get even more rectangular empty spaces.
Just be careful to finish to count the emptyness before starting to count the remaining stones.
A bit of practice with yourself may help to feel more confortable.
A word of advice, do these kind of permutation under the scrutiny of your opponent as it can be easely mishandled (and a way then to cheat)
Besides i keep in mind a video i could take if i have an opportunity to illustrate Chinese scoring IRL but these days my opponents use that: modern Chinese counting IRL