Once the new 110-ish gallon water tank is done, we'll be able to comfortably go at least a week without needing anything more than taking the dog ashore.
The 70 gallon holding tank is easily good for about 10 days with 2 of us on board, but could probably be stretched a few more days if we're really careful. If we're not moving around much (not burning much fuel) and don't mind carrying water back to the boat on some of the dinghy trips with the dog, waste capacity would be our biggest limiting factor.
We know from experience that provisioning food for 2 - 3 weeks is easy for 2 of us and we could certainly provision for longer if necessary. In general, if provisioning by dinghy is acceptable, we could probably stay away from docks nearly indefinitely, save for fuel and pumpout stops.