Other than Friday and Saturday, I’ve never had any trouble booking reservations same day or day in advance, anywhere west of the Mississippi River. There are exceptions of course, but I’ve taken 6 week trips out west and paid for camping just 3 nights, between harvest hosts, ultimate c.g., rv Parky, blm etc…. My favorite campgrounds are c.o.e., they’re always on water and with the American the Beautiful pass, they’re half price.