Do I need to reserve in advance?

We did our first long trip in the RV to Orlando from Houston this past Thanksgiving. We left not knowing how far we would make it that day driving, so waited until about 2pm to call around. What I learned - you have to keep in mind the popularity of the city and the time of year. I started calling at 2pm due to most close at around 5pm, earlier on the weekend. We ended up stopping on the way in Biloxi, MS at a casino RV park which was pretty empty and then drove the rest of the way to Florida the next day. It was just a standard, no perks, park. You had a gate to go in and they gave you a code when you called, and a gate to go out when you left. Never saw anyone that worked there the whole time. It was probably a 5 on the scale, but it was only $23 a night, and was empty. We drove the rest of the way the next day, and on the way back stopped at that same park (it was about the same - empty), and then stopped once more in Lake Charles, LA. THAT was hard to find a park. We were about to have to dry camp at Walmart, I must have called 6 different parks who were full. Finally I was referred to a newer park that wasn't online yet and we were able to stay there.

Point being - depending on where you are going and when, it could get pretty difficult to find one, BUT you can always dry camp for a night and try the next day. If it were me, I would call ahead of time and try to set up places where you would LIKE to stay rather than having a chance of being forced into the only one available. It is a learning experience, so, good luck!!