Maybe this wouldn't work well, but can't you just strap some ice packs onto your motor? Assuming they will fit and not fall off.
There's lots of different designs and options for cold packs that would work. I'm going to try that as my 1018z seems to get a bit warm in these 90 deg temps, even after 2 miles of <600w riding.
As for the gearbox on the 1018z, someone on this site said to add more grease to help keep the noise down. Will bike bearing grease work? How much to add? Any other ways to reduce noise without suffocating the motor in insulation? lol