If you go 99 to Fresno and up the 41, you have a nice drive, not too difficult to the valley. However, if you do the 395 and go in on Tioga Pass, the scenery is spectacular and it is a little steeper. I don't think you will have any problems going either way.
My very first experience with a motor home, ever, was with a rented 1976 Open Road Class A. I was nervous but had no problems. We went up the 41 and out Tioga Pass, which is just shy of 10K feet. After that we went to Lake Tahoe.
Oh, and I had 10 people in the MH, too. It was powered by a gas Chevrolet 454 ci V8 and ran great. 3 gas tanks.
You might want to visit the film museum in Lone Pine (on the 395). Worth your time, especially if you like old movies. As a confirmed old fart and afficianado of Film Noir, well, I had a great time. They have the actual 1935 Chevrolet coupe that Humphrey Bogart drove in "High Sierra".