You should be aware, that in addition to Mariposa Grove now being closed until fall, the coastal portion of your trip will also have to change from your original plan.
CA-1 is closed at Big Sur due to a collapsed bridge and will not reopen until at least September 2017. Essentially, you will have to use US-101 from Monterey to Cambria. You can follow the latest here: http://www.roadtripamerica.com/forum...-Big-Sur-Issue!!!