Another way to avoid cabin fever and cheaper than a new boat. Agree that every so often, set any time frame you want, you'll stay in a hotel or motel. Vacation for a night from the vacation.
We were worried and our first boat after moving to the coast was a Riva, not exactly designed for space. We said we'd spend one night a week in a nice hotel. Came time we had no interest. Two years later we've cruised many thousands of miles and never once chosen to stay in a hotel while doing so. But we had that out had we needed it. We didn't know.
Also, we explore on land. We walk. We take in as much as we can. We dock at marinas, sleep on the boat. But during the day we're out and about. By the end of the day we're a little tired and are glad to get home and collapse on our boat. We go into every place with a list of things we want to see. You may think you've seen all there is, do some research on line and you'll find more hidden gems. And mostly absorb the feel of the community. There is no where we've been we couldn't enjoy going back to. Now we typically stay somewhere two or three days. We do it intentionally to leave things for next time. But most places can keep you busy for a week or more. We also explore in our dinghy. Just ride around, go inside creeks and see what's there. We can spend a day easily doing that. For instance we love Savannah. But most visitors never see all the forests all the natural habitats. They don't explore up the river further or around all the islands. We've spent three days so far doing so and next time we're there I'm sure we'll take another day.