The problem with 4.5 is that it is giant spread (since it is the top end of most competitive USTA leagues). I know people who have played a lot and have worked up to 4.5 after 10 years and others who have serious credentials (varsity college /semi-professional players) working down the rankings. Without meaning to insult those working their way up the rankings, the players are, in no way, comparible.
But I agree with your general premise. There is almost no way you (4.0 combo) can hurt the 4.5 with your shots and he is likely in good enough shape to run the whole court.