Peltier reverse polarity
You can do this, the Peltier will be just fine and the orientation doesn't really matter (efficiency will be the same). Just keep in mind that Peltier elements don't like being switched on and off a lot, but as long as you only switch it once per minute and don't use PWM to control it, it should be fine. Changing polarity once a minute won't hurt the Peltier either. Also, don't underestimate the amount of heatsinking your Peltier device will need.