There's really not much in the area.
Up until about 10 years ago we would stay at the Visalia/Sequoia KOA on Avenue 308 at Road 76. It's far enough off of the freeway so no noise. It's an older campground but acceptable. The rvparkreviews.com are a good reflection of what we experienced. We no longer go in that direction is why we haven't been there in 10 years.
If you don't mind a drive our favorite in the area is near Three Rivers
Here's the website: http://www.sequoiarvranch.com/
It's about 25 miles from Hwy 99 so it would put you about 35 miles from Hanford.