Subarea cutout producing different cutouts when rotated poles differ

First reported by @afinnen:

model 1:

model 2:

In the above examples the same cutout region (based on real-world coordinates) is being applied however the models are producing different results.

Comparisons by @afinnen plotting the cutouts onto the larger domain show this:

This could arise because only the corners of the cutout are rotated, so the areas will not overlap for the same rotated pole.

An initial approach (suggested by @afinnen) could be to create a 2D array with unrotated lat/lon pairs for each point
Create Boolean version where points set to true where both lat and lon are within the user defined range
use the boolean array to mask the rotated pole
create a copy of the rotated cube replacing the original data with the masked array.
use that cube for plotting