OP, it can be done, but you'll have to compromise . . .
First, I live in Mariposa, CA which is about an hour from Yosemite National Park. My wife and I have been to the park several times and have camped in the area for a couple of years. So . . .
I suggest using a web application called RV Trip Wizard. It's great for planning RV trips as it lists RV parks, travel distances, reviews, maps, etc.
From Anaheim, I'd suggest you travel to Three Rivers Hideaway campground. It's near Sequoia National Park, but it is a 230 or so mile drive.
Next, I'd camp at the Mariposa County Fairgrounds or up Highway 140 (going to Yosemite) at AutoCamp Yosemite.
From one of these two campgrounds, take the YARTS public transit bus to Yosemite. Then in Yosemite sign up for a bus tour of the park. When you take the bus into the park, you do NOT need reservations.
Plus, even with reservations, you do NOT want to drive around Yosemite in a Class C RV.
The time to make reservations is NOW.
Finally, your Class C will probably be 30 amps.