The location of the camp where Ana-Lucia digged the pit is 3 days (of continuous walking) away from the Tail crash site (stated by Bernard in S02E07).
The Taillies need one day to get from the pit to the beach and another one to find the Arrow. Later, they seem to travel this distance in much less time (see S02E03).
They go fishing at the beach (see screenshot), so it shouldn't be too far away from it (see S02E05).
At the moment, I'm still unsure about its position and start to return to the theory that it's located in the South or South-East (notice the position of sun/shadows in the screenshots)
Edit (02/08/07): Screenshot of the main island seen from "Alcatraz" in S03E07
