Hey! So this might not be be perfect but it’s a reasonable option, I think. Check out the course for the buzzards bay triathlon down in Westport. I live just north of boston but grew up on the south coast and ride out to Westport when I’m visiting my parents. It’s 14 mile loop but it’s about as flat as you can get, minus a couple of small climbs, and generally can be done with no interruptions. There is maybe one intersection where you may have to stop but generally traffic is really nonexistent. There’s ocean wind to contend with but it’s a great place to ride