10.0 would be OK in a larger enclosure. The idea is that the chameleon isn't forced to spend a ton of time in direct contact with the intense light. A smaller enclosure does not give the animal much choice of where to spend it's time and it can be "forced" to stay in the direct path of the light. The idea that a heavily planted enclosure is best is from the fact that there is more chance of thermo-regulation. In this case, and the chameleon should be able to seek out the area that it wants to either warm up or cool down. The more densely filled enclosures would tend to mimic dappled sunlight, but most of the intense rays of the UVB are within the first few inches of the screen and there usually aren't many leaves up that high. In other words, the chameleon would not get the protection from the UVB in the most densely planted enclosures if it spent it's time at the top. The best way to tell for sure would be with a solar meter, but in this specific case, the enclosure is too small (in my opinion) for a 10.0 and the animal too young.
