Dave, you might want to peltier cool the Toucam as well. Philip Davis (no not me) has an excellent site detailing both the long exposure ToUcam mod and a peltier conversion of the ToUcam as well. He hasn't yet posted any meaningful test results from the conversion so I'm unsure of how effective the mod is.
http://www.philip.davis.dsl.pipex.com/peltier_mod.htm