Using a space heater looks like it would work well with this cage. That way it won't get too hot but you won't have to worry about the bottom not being as warm as the top, it would heat pretty evenly. The one that I use shuts off if its tipped over and doesn't get hot to the touch so if something were to drop on it, it wouldn't start a fire. I got this kind so it would be safe to leave on if I leave the house.
On a side note I really love your hedgies cage set up and the bedding is very cute and well coordinated
On a side note I really love your hedgies cage set up and the bedding is very cute and well coordinated