Hello Steve, I was going to suggest that add another bulb on the cool side and use a taller basking area, I see you are exactly doing that now.
Make sure you wait about 45 min for the temps to stop rising before deciding the final temps. Another thing to keep in mind is that the MVB's have a 2 to 3 day burn in time so the temps will be hotter the 2nd & 3rd day. Also make sure the probe end is actually resting on (touching) the basking log. You might need to use a piece of scotch tape on the wire near the probe but not touching the probe itself. Would also be a good idea to push the thermometer part as far to the cool side as possible to get completely accurate readings. Those AcuRite thermometers are great, I have 2 of them and they register very close to my temp guns. What are you getting for a humidity reading?