If you are still looking to do this I'm interested. I have yet to pick up any Brandon Sanderson books but they are on my to read list and by what has been said here have jumped right up.
If you want more general GRSM rep and like Sci-Fi and Magic I would recommend Glynn Stewart. He has done quite a few series and a few one short as well and pretty much always has some sort of representation in it. If I remember rightly, and it is hard to check with no wiki or anything, the main Character of Castle Federation is explicitly Demi-sexual. I don't remember if there is any Aro rep in the books but honestly I devour them so quickly I don't always notice till my reread through so it could very well be in there. He certainly doesn't shy away from Enby, Ace and other less well known rep so I imagine it could be in there.