Your best bet
https://www.ebikes.ca/shop/electric-bicycle-parts/motor-hardware/cooling-mods/statorade.html
https://www.ebikes.ca/product-info/statorade.html
The problem of using the hanger to cool it is that the steel of the stator is not a good thermal conductor, and the section the heat has to travel is small, with Statorade you transform the whole can in a heat sink, the results in eBike hubs are impressive