We retire in January and will be hitting the road for two years by RV. Then we will spend a year doing the great loop on a boat. We have been rv traveling for two years now; we boat traveled for two years before that (vacations and weekends for both). We had the benefit of living on the chesapeake bay and having a boat small enough that it could be towed to places like the keys and the outer banks.
Honestly, there is a much smaller learning curve to an RV than there is to a boat. You already know how to drive and you know the rules of the road. For a boat, you will need to learn navigation, tides, docking, and driving. And that is just a power boat - a sailboat takes even more learning (wind, sails, tacking, etc.).
You might try renting an RV for a week or two, then doing a bareboat charter or something similar for a week or two. Both will give you an idea of what is in store and will give you a taste of the different types of living.