Given that there is no weekend this year for the fourth, it might be easier. Just an FYI...we've NEVER had a problem finding a campsite during the week. We just get there early in the morning, and take what's available--which may be Hodgdon Meadow, Porcupine Flat, etc. Don't arrive Friday afternoon of a three day weekend and expect to find a site....but if you plan ahead, and arrive early in the day, you should be OK during the week.
Of course, you will now take my advice and get skunked! grin
Check our our website: http://www.backpackthesierra.com/
Or just read a good mystery novel set in the Sierra; https://www.amazon.com/Danger-Falling-Rocks-Paul-Wagner/dp/0984884963