That's really an interesting approach Mike, here is how I approach multi (note that I'm not nearly as good as you (yet

))
I just use standard roman rooms with 10 locations in each room, 2 images per location in my room, letter pairing gives me 4 letters per location. So basically 3 locations max for edges, 2 for corners, thus 2 cubes per room.
For flipped edges I do the same as you, I just have the image upside down, depending on whether the first letter is flipped in my image, the top half of the image will be upside down (aka a person will be flipped, top half only, if you can imagine that) and if it's the second letter that's flipped, it'll be the bottom half.
If two edges are flipped, and permuted, I just (since I solve edges first) put on the blindfold and do a pure two flip. Haven't really decided what to do if only one is permuted but flipped, probably new cycle (if I'm doing multi)
If regular 3x3x3 BLD then I'll just visually remember that it needs to be flipped
Corners, I know pure twists but I never apply them to corners, due to me being afraid if I'm twisting the incorrect way

. Should really start doing the pure twists, it would save me a lot of memo for those situations.