Send me a P.M. if you want details. I do that all the time.
Last year I did it once a week, to the Canal and back to East Providence.
Forget route 6. I've done it on route 6 too. That is the worst possible bike road in the area.
Up above New Bedford airport that road, can take you out to the cape very nicely. I do go through Rochester. I don't use 105 but I do cross it. From East Providence I use three nice routes or a variation of them.
The Rubels bike map of that area is something you must have !! It can be ordered on line. With that you can make your own route in ten minutes. You really need a map even if I give you detailed instructions.
To try it without a map is silly. Road signs can be stolen, road work can have detours etc.