This might turn out a interesting thread. :-)
Learn as much as possible about foraging, shrooming and legal sorces of animal protein if you are carnivorous. Grow things in the boat, like sprouts, cress and sunflower shoots. Grow things on the boat. Plant things in areas you know you'll return to in the future and mark it down on a map. Always start a shopping spree looking at the short date shelf and plan meals around your finds there. Only fill kettle with the amount you need during the season the stove isn't lit. Amazing how many that boil a half full kettle when they only need one cup of tea. Solar is awesome! Turn the fridge off when outside is fridge temperature. Think, do I need or want this when the urge to acquire something pops up. If you need it, can you make it your self? If you can't, can you learn how to make it? Knit! Wooly socks and a cup of foraged tea saves fuel. Eat more soup. Anything can be tossed into a soup :-) Learn to preserve food when in plenty to forage or in season and cheap, for when it is not. Cure, dry, ferment, pickle, jam, preserves..... Swap things with other frugals :-) To talk to people, help out and be generous, is often surprisingly rewarding.
But be sensible. There's a lot you can do without going over the top. You want to be comfortable. Not silly frugal :-)