Roads around Dickinson will be under water by Friday night(the rain will start Fri morning), and all the ship channel bridges will be closed due to high winds, forcing all remaining traffic further west to already clogged roads. The storm surge may have already reached I-45 before dark, even if the projected landfall stays miles west of Freeport(though it moved east to almost Freeport at the last report.) I strongly, strongly recommend getting out of Dickinson tomorrow.
I concur with your analysis, Dickenson is no place to ride out this storm, get out now.