Travel from Naoshima to Osaka via Himeji

We will be spending a night at Naoshima. Ideally we would like to go to Teshima Island also, then head back to Osaka, also stopping at Himije Castle.
Am wondering if this is doable or do we need to spend another night either at Naoshima (expensive) or Okayama?? before carrying onto Himije and Osaka? Thanks so much for your thoughts.

You've checked the Benesse website, and looked at the ferry schedules, yes?

Basically, they give you your answer.

I can't remember where you can catch a ferry to Teshima from (HEY! wait a minute, with just a second's searching, I find this: http://www.japan-guide.com/e/e5440.html#jump_access )

If you don't want to stay two nights in Naoshima, you can stay in Uno.

From Uno to Osaka it take around 2 hours 30 minutes by JR train. So you can move to Osaka on the day after sightseeing Teshima island. And if you have a time, you can stop at Himeji for see Himeji castle. Have a nice trip.

thank you both for your help.
it's very kind of you to take the time to do so.