RVing is far cheaper than boats. Marinas charge by the foot & charge extra for power & pump out. We measure fuel in MPG. With a powerboat it does not take a very big boat to start measuring in GPM. RV storage is nothing compared to boat storage & haulout costs. Anytime I see an RVer moan about RV costs I have to smile. Try a boat. Break Out Another Thousand.
We used to do over 40 nights a year onboard our 32'er. Loved it. We were weekend warriors on the water. Every weekend was spent with like minded families all rafted up just off a quiet island beach.
At one point we considered getting a 40' or so trawler after the kids grew up but when it got closer to decision time we ran the numbers the boat just did not make sense to us. The daily costs are astronomical compared to the RV & there are so many places a boat simply cannot go. Anything further than easy walking distance from the water is not really an option. Try going to Alaska from the East Coast in a boat. Anywhere there is water somebody has a boat rental business with a boat suitable for the area.