I wish you all the best with this Sir, but I really feel you are in way over your head being a complete novice and refinishing a four color RV. Take some time to read up on the forum here. It's the best education you can get. There is no bad info here as many of us are Pros and bad info gets called out and corrected rather quickly. Take what most paint jobbers tell you with a grain of salt as they don't usually have any experience using the products they sell. You are really like a babe in the woods and you need to gain some knowledge before you tackle something like your RV.
Again best of luck to you. Hope it all works out for you.