Been on a few two week cruises on Chesapeake bay, but we usually end up going to a marina every three or four days to keep the Admiral happy. Your biggest problem will be the holding tank size, which fills up quick, even with just two people onboard. The engine burns less than a gallon an hour so even if you motor a couple hours a day into/out of anchorages (this will also feed the fridge drain and keep the water hot) you will be fine, but keep in mind than once you get much less than 3/8 a tank, you can get a gulp of air if motorsailing in big chop and kill the engine (which is eventually self bleeding if you keep it level). I carry a jerry can of fuel on long trips just as a reserve due to lack of baffles/pickup location. 35 gallons of water (plus what is in the water heater when the tank runs out) has always been enough for us to outlast the holding tank, but this will depend on your personal habits. Never been more than a couple miles offshore in the 310.