Just to throw a wrench into the discussion. How much resupply do they actually need, depending on their weaponry?
Ships reliant on missile tech need resupply of missiles, that is a given.
Repairs to hull and other systems will eventually need replacement parts, but a lot of those could be brought with you. Cold watch can replace casualties, and autodocs and fast heal can repair people pretty quickly.
Fuel is available if a gas giant is around. Yes a gas giant is a spot to defend and lay traps. Other fuel sources are water asteroids, moons, other ships. If a ship is not looking to Jump out it needs only a few tons to keep it running for weeks.
Oxygen and ice cubes are available from the same sources, the Harrier book explains that.
Food can be brought with the ship, enough to last for months if there is cargo space.
Other options for food is a biosphere or production facility on-board the ship. This reduces life support costs as well in some cases.
All in all a spaceship could be stocked and manned to sneak about for months behind enemy lines if you packed creatively.
How often are you thinking they needed resupply, and what did you think needed to be supplied?