When my kids were kids, my family camped in Yosemite Valley for about a week or so almost every October for years. Even that late in the year, and that long ago, you had to get online long before your trip to be sure of securing a spot in one of the valley floor campgrounds (or maybe even to hope to secure one). In other words, camping inside the park in the summer is very problematic. Best shot is to plan on staying outside the park and ride in (early) for day rides. The lineup at the entrances can get very backed up and slow too, as in all the popular National Parks at peak season. The traffic inside can be slow and heavy too. If it wasn't about the most gorgeous spot in the world, it almost wouldn't be worth all the trouble. But it is.
p.s. There are beautiful parts of the park that can be enjoyed from the road and not as crowded as the valley floor, like Glacier Point and Tuolumne Meadows, but speed limits in the park are low, and there's always the traffic. It's something to see, for sure, but the really good riding is outside the park. Lots of it.