If you are indecisive (as I am) and aren't sure that you should book a stay on this tugboat, just book a stay on this tugboat.
The Aulneau is charming, unique, and truly lovely. Daniel is a considerate host, and I felt welcomed into--and comfortable within--his space. All of his communication was clear and helpful, he was good natured, and he left some treats which were thoughtful (and generous).
Although Daniel offered several recommendations for restaurants, I ended up staying on board and just enjoying each of the different "rooms" of the boat, each of which was cozy. Although the marina was a little loud on a busy Friday night, I slept soundly and felt well rested.
The composting toilet requires no special bravery.
I did pay for closer parking. As a solo traveler who had planned to leave quite early, I felt a little better about something less than a block away. If you make that same choice, don't pay the cash price. Instead, pay online.