If the API accepts only 800 by 800, the aegument youre making is "fix it in the harness".
I don't think the n by n subgrid fixes this the way most harnesses do, as it'll fail to count things if you have more overlap and fail relatiomships if you have less
That seems weirdly specific?
And if you are counting things it should be trivial to note the position of your items and not double-count them, no?