I do the same thing. I use the lowest wattage I can get away with. Not only is it less likely to fry a snake (not only does it not get as hot but the surface area is smaller) but it is also a lower fire risk too. I use a backup on/off thermostat hooked to my proportional so if the main thermostat fails, the on/off one will shut it down. Can't be too safe with this stuff.