Hi Christo,

Outrunners don't have much aircooling in a narrow hull like a rigger, though the build in fan will help.
If you have the time and resources, make a watercooled motormount, so you can at least cool away the heat from the stator.

The picture shows a commercial version, but you can make your own out of aluminum strip and drill a hole to fit an aluminum tube, where the water runs through,

Let me know if I should provide a pic of that.

Regards, Jan.