It doesn`t matter whether the people breeding them tell you the dragon can move as close to the MVB as it wants, you need to follow the manufacturers instructions, THEY know what`s best/safest! I believe this enclosure is far too small for this bulb, as I`ve already said.
The main problem you have with getting the temps up is that the MVB is outside the enclosure with screen between it and the basking site, in effect much of the heat`s lost to the room, and if the holes in the screen are less than 1/4 inch much of the UVB`s blocked, too!
I haven`t used that particular brand myself, so I`m not sure of the precise details on minimum enclosure size, but these instructions are for the "Powersun" MVB`s:
http://farm8.staticflickr.com/7146/6...c7a45d86_z.jpg