Can confirm. Im in Houston and do what you mention with said track record. I cant get 240/hr, but can get around 175-180 most of the time. I base my rate on 85% utilization of myself. meaning Im working 10 and a half months per year.
That seems pretty good to me for Houston.
As for the hourly rate, I would always accept more but have no real complaints. Getting back to the original post that made me comment, 240/hr for a freelance web designer seems unrealistically high, especially in Houston. I dont know the market well enough in other parts of the country though.