As mentioned above Labor Day weekend is almost always reservations required anywhere in the country.
The only 'Reservation Required' area would be if you want to be somewhere under the total eclipse on Aug 21. Roughly about 100 miles either side of a line from Jefferson City, MO to Nashville, NT to Columbia, SC.
We have purposely delayed our return to Texas from Washington state until after the total eclipse. Federal campgrounds are totally booked, and private campgrounds are booked at outrageous rates.
It is a rare one-time event, and I don't blame RV park owners for getting the most money they can.