you do realize electric motors still get hot
Lot’s of cooling air at 50,000+ feet.................
You obviously don't realize how piddling "hot" electric motors are compared to jet engines. The burning fuel in the combustion can of a jet engine gets as hot as 3600°F, and the exhaust gas at the engine exit (which is completely visible in ordinary a/c) can be 1000°F.
Show me your electric motor that can match those numbers.
Regardless, the temperature of the engine itself is irrelevant compared to the heat of its exhaust gasses because the a/c's skin can be shielded from the engine's heat, but there's no getting around the fact that at some point you've got dump the jet engine's 1000° exhaust overboard.
And that's a dramatically bigger ask than disguising anything coming off an electric motor.
The XRQ-73's only "visible" sources of heat will be the air getting heated as it passes through the ducted propulsion fans, and the heating of the a/c's skin from aerodynamic drag.