Oh and do you think that I need a heat mat under there to help the heat and humidity during winter?
Unless your going to retain summer temps 22c to 28c then dont be too concerned about humidity, you dont want it too humid in cooler temps or you'll end up with sick frogs.
If you keep them room temp (cooling) then choose an unheated area of the house. The reason for that is that if you house them in say ,the loungeroom over winter, where you will have heaters etc running, you will find they are too warm for proper overwintering (not moving much for days and not eating) but not warm enough for normal activity and feeding, in which case they will waste away and starve to death.
so, either cool in the coolest area of the house or retain summer temps and humidity and continue feeding.
This depend on the age/size of the frogs too. Tiny young frogs, like tiny reptiles are best not cooled till attain size and condition. There are several methods of heating.
(a) a large enough water area to contain a water heater set at 25c (keeps air slightly above that dep on ventilation) moving water will also create summer level humidity.
(b) a lamp above Not too hot/close, max temp 28-30 and only in one small spot (one end) red or blue at night
(c) heatmat/cord . This presents a problem in that tree frogs rarely sit on the floor, you cant put a heatmat in a branch! lol
Remember if you cool, your light source/levels should time according to winter adjusted as u go.
Same with summer , use a timer and adjust/create summer daylight hours.
Use a thermostat,with any lamp, more accurate the better. best luck