thermoelectric:peltier cooling does work (see Peter setup), i have tried 3 peltier in the row without sucess only because my heatsink on the hot side was to small and i need a fan when in static , the heat was going back to the cold side and the esc
i let go this type of cooling only because i have enough air cooling just by the heat sink on top of my case
cpu water cooling may work in closed loop, but this is starting to be heavy