Keeping snakes in a room that is 60 degrees is just as safe as playing in traffic. If your power cuts out, your snakes are done. Moreover, its going to be near impossible to keep your ambient temps in the lower 80s, even is you set the heat to 95 degrees.

The first thing I'd buy, before you get your rack, is a space heater with a Ranco or JC thermostat and get the room warmer. That will make it 10x easier to keep your temps up. I keep my room at 82 degrees year round, makes life a lot easier.