Last summer I traveled from Minnesota to Eugene Oregon and back. We didn't have a set itinerary outside of a few days in a hotel while we attended the World Track and Field Championships. We were going to drive each day and setup camp whenever we felt like it. Some nights were boondocking, some were in campgrounds. No real problem at all.
We got there earlier(Eugene) than expected so we had to find a campground.
Getting a hotel room for a reasonable price was impossible, same as the campgrounds. We stayed a couple of days at an RV park which was not a great stop, it was the worst place we stayed on the trip. It was almost like camping in a parking lot. But it was safe, and it did fill up daily.
We got in without any prior reservation. Just the nicer campground locations were full.
That was fairly typical on the trip, if we pulled in before 4PM, we had to problem. We did pull into a campground outside of Wallace Idaho about 6PM and got the last spot available.