When my boxies are inside for the winter, I keep them in a planted vivarium. I tried everything and nothing held humidity as well. That's why I was interested in your little water pond. They all go out for the summer, and this year will be the first time the Juvies will stay outside and hibernate. I just use regular tropical house plants, a mix of soil and peat moss, and green moss on top. I don't use any hides. They dig down in the moss. For light I use a 10.0 UVB, or 5.0 on the smaller vivs. For heat just a regular day glo.
If my smaller guys don't come out to eat, I just mist the whole viv and water the plants and they come out. When it rains outside boxies come out to eat. Try misting the enclosure and watering the plants and you might stimulate him to eat more.