Just took a 2 week trip last month. We used Good Sam, KOA, and REC.gov apps.
For the cities we planned on visiting for a few days, we made reservations 2-3 weeks in advance. For the stops in between, we just called a couple of hours before we got there. Never really had a problem getting a place to rest. Get an RV GPS, we didn't have one, and wished we would have. To be honest, we really only needed in populated cities, like New York City. They have lower clearance bridges / crossover. More importantly, give yourself plenty of time to drive. If google maps says travel time is 7-8 hours, add 2 hours. You'll probably drive slower than anticipated, I drove mostly 60-65mph and mountains & curves will slow you down even more. Stop driving and check in by 6-7pm, give your time to setup and enjoy the camps. Have fun.