Maybe use for the two days in Italy normal individual tickets.

There are two major Railcompanies in Italy
Trenitalia (state owned) operate a Highspeednetwork and many local routes
Italo (NTV is  private owned) and operate a Highspeednetwork between the major cities in Italy.

RAIL Passes do not include ferries-many though give a little discount (which they also give to all ju/senior in general). It may very well be that ferry nr 2 without disc is still cheaper in the end on final price. Due to current fuel cost all charge extra surcharges for that