Get the water temperature from Tahoe and fill the bathtub with water at that temperature and add a slight breeze with a fan and have her spend some time in it. Get the forecasted air temperature and set the house thermostat to that and have her simulate boarding by standing in front of a fan set to high after she gets out of the tub dripping wet. Then ask her if that is what she looks forward to. More than likely you will run around the lake with your heater on and never get in the water. You could take a TV, inverter and rabbit ears and watch the game from the boat.