I would think forced airflow over the heatsink would be more effective like a small computer cpu or graphical card cpu fan heatsink. They can be very light and quiet. However like any electric motor, it is going to draw some runtime off your power supply.
With little enough air in the system, the liquid should be enough to move the heat. In fact, some people have done just that with water cooling computers: no pumps or fans, just a radiator, and thermal expansion and contraction giving a pumping effect. What you get with liquid/vapor is the ability to actually
move the heat, so that a short thermal path to the liquid/vapor gets around common dissipation inefficiencies.
You could put a radiator at the rear of the body, for instance, and be able to handle quite a bit more heat than with a large metal slug directly attached to the emitters, just due to reduction of thermal gradient and thermal mass near the heat source. Given that the water must be able to expand and contract, however, and that getting a perfect sterile sealed environment and mixture will be difficult, a heatpipe would offer most of the performance advantage, while being a truly sealed, no fuss, heat transfer mechanism.