Ditch the heat mat, whites and most frogs I've had like to bask. Also, when using a heat mat they do not really warm the air temperature and mostly just the glass attached to, so although the middle of your tank is that temp, the glass where the mat is attached to may be a lot hotter. I'd use a 25-40w zoo med daylight blue or red bulb and then a 5% UVB for the frogs lighting and UVB needs. The heat lamp will create a basking spot but will also warm the ambient air temperature. If your tank drops below 65f at night you can use the red bulb or a ceramic but there's not need to use the heat mat as well. If you choose the ceramic this should be controlled with a thermostat, such as the microclimate b2me