They also might be on the wall because that's were the fresh air is, and hence it's a little cooler. In my experience, 79 seems a bit high for a constant day time temp.
As for the bark thing, I have two sikorae that love sycamore, although they don't blend well. The two places I find them the most though, is on the back side of chunks of oak bark that I have, and on the trunk of this sapling that I cut off. Thats kind of my own personal secret, is to find a young tree, at least an inch and a half in diameter and with pretty smooth bark, and then cut it off at a point where theres several branches to lead to other parts of the tank. They may not like your vine twists because there is no place for them to lay flat, so they would have to suspend themselves over the gaps.
Hope this helps
Tarl