Additionally, the use of an external cooler is absurdly inefficient to begin with. If you're lucky, you'd have something like 8 W/m^2-K on the TEC and another 8 W/m^2-K on the equipment side, assuming you can get all the heat to the heat exchanger.
Even if you designed a TE cooler that was mechanically interfaced directly to your heat exchanger or, even better, your heat sources, your overall efficiency would be substantially better.
TTFN