In last 3 years we made couple transcontinental vacations and spending 8-9 weeks on the road we never made advanced reservations.
When I was planning next stop - I would go on google maps and after finding list of campgrounds, I would go to satellite mapping where lot of areas had 3D option who would allow you to "fly" over and actually see what you are getting.
Than sometimes you get nice surprise. Only beware of long weekends in prime locations who are sold out 6 month in advance, but having good internet you still can find a cancelation.
Having 6000 lb camper and dogs, I often preferred dropping the camper and leave it with AC running for dogs, when we would drive pickup for exploring the area, or dining.
With some practice dropping off is 5 minutes, loading alone takes about 15.
Than took me 3 years to figure out my Ford 360 cameras have trailer option who makes lining up a breeze.
Whole idea of having TC is avoiding car rental.