Cycling Shimanami Kaido in December

I am thinking of extending my trip to Japan to include 2 days of cycling in December.

Is this advisable in December? Does it rain a lot?

Was looking at riding to Imabari on one day and am open to another route for the second day.

Would it be best to base myself out of Onomichi or would it be better to stay one night in Onomichi and the other in Imbari?

Is there a way that we can get luggage from Onomichi to Imbari on the same day?

Thanks.

Weather maybe no problem but already winter air feel wind cold just no fall snow.
http://www.go-shimanami.jp/qa/answer.html?qa=kion

No luggage sending service.
http://www.go-shimanami.jp/global/english/contact/