It can be done but there will be sharp turn after sharp turn going over all the sea terraces. And where the signs caution vehicles to go 15 MPH, believe them as they are accurate and they will keep you in your lane. I would not do the route in anything longer than 28 feet but logging trucks still travel this section of road so it can be done.
Campgrounds are another possible problem as most of the campsites at the state parks along this route will not accommodate a 45' motorhome. Check on private RV places before you head out.