Yeah for sure, I think that's going to be the strategy for the more distant bits. Or heck, even the rest East Cambridge.
I'm having that trouble with East Arlington. It takes a lot of my running time to get out there and back. I can imagine Cambridge is even worse...
I think the bow-tie shape of Cambridge would make it pretty accessible if you lived just north of Cambridge Common. Elizabeth Warren would have it easier than I do.
A number of years ago (before I had a GPS watch) I was trying to do this with Lunenburg, and my intent was to do it all starting and ending at home, but I definitely don't live in the middle of town. Eventually it seemed like the remaining stuff was mostly distant and requiring out and backs on busy roads, and I kind of lost interest.