Yes I know what you are saying in England we dont have any tree frogs native to us but people I know keep various ones outside in greenhouses all year round. I have kept Whites t-frogs outdoors in a flexarium for a few weeks during the summer you just have to use common sense fill them with plants and put a water dish in they can look quite good. You cant spoon feed people all the time. Give them an idea of what they can do .You're going to be 2 buns short of a picnic, if you want to put your frogs outside at 90f in full sun with no shade and no water