Do remember that the Staten Island ferry is free and gives you a great view of Lady Liberty.
I would dispute that! I've heard many number of people that have said 'well that was disappointing' in the view of the SOL from the Ferry. The statue is about the size of your thumb when viewed from the ferry!
If the OP doesn't have time for a visit to the island - I'm not seeing any 'ferry transit time' in their list (unless they have included it in the standing in lime and time on the island - then a generic boat tour that goes around it might be an alternative - no security screening for a start!