Okay so the verdict on custom winding: No go.
I tried 3 different wire sizes, oem ~.5mm, larger .65mm, and much larger .81mm. The larger wires dont wind as well, the OEM sizing seemed to work best.
The oem motors are tightly wound, they seem to be wound very well. Atleast with my winding skills, I was not able to fit any more copper than the OEM motors come with. Additionally, I tried drilling out the stator. I tried drilling out the stator with diamond grinding bits. I tried using an angle grinder and dremel to widen the stator gaps to fit more copper. None of it helped much, and it damaged the laminations in the process. I also had significant issues with stator shorts when winding, especially when trying to cram in more copper.
I was able to wind a couple successful motors, but they are approximately the same spec as OEM, no improvements.