Good intentions, but you are just like me...
... prone to putting mouth before brain when it comes to ideas.
Think about it. Below ambient temperature = condensation.
Current form factor = limited thermal dissipation to even couple your customer option too (external air pumped in or external coupling of a heatsink)
There are already at least one water cooled docking station laptop on the market. But it requires the watercooling loop inside the case to begin with (then is docked to the res+pump+fans+radiator).
PS, I know I've probably also spoken before thinking long enough on this reply too! ;)