Using a very simple 2A Peltier module salvaged from a minifridge intended for automotive use, I did some testing to determine practicality.  With a very minimal test rig (a coffee pot, the module itself with fan and heatsink, and a 12V power supply) I brought a liter of water to hot and cold extremes.

The results were better than I ever could have expected.  Despite being a cheap and very underpowered module compared to the Laird ones that will be used in final project it performed wonderfully.  It achieved a maximum temperature of 69C and a low of -1C, which is quite impressive given it was never meant for such extremes (The Laird is).  As expected it took some time to reach these temperatures given the lack of insulation and low power, but it shows the design is practical.