I am not sure of your route. The 'fast ferry' to Michigan leaves from Milwaukee, not Kenosha. You have an option to go to Manitowoc for the ferry but I am guessing you are planning on the ferry from Milwaukee.

Once you hit Albany, there appears to be only one climb before NYC if you take NY bike route 9 following the Hudson Valley. There are shorter options that might be hillier, I did not check them out.

It would be out of your way but the bridge over the Hudson in Poughkeepsie is cool to see. I just rode on part of the Erie Canal, it is in good shape.

Crazyguyonabike is often a good resource to learn routes and equipment. If you have not reviewed that site, you may want to check it out.