"How odd," Xandren says, as he drops the goblin to the ground.
[sblock=Rest]Warforged only need four hour restraining from strenuous activity, and are aware even while resting. So the quickest extended rest, doubling up with Xandren's aware rest to get a patroling perimiter guard, is 7 hours (assuming that patroling is strenuous... if not, he can take the whole night).
Hour 1 - Xandren patrol, others asleep.
Hour 2 - Xandren patrol, others asleep.
Hour 3 - Xandren patrol, others asleep.
Hour 4 - PC1 patrol, Xandren aware, others asleep.
Hour 5 - PC2 patrol, Xandren aware, others asleep.
Hour 6 - PC3 patrol, Xandren aware, others asleep.
Hour 7 - PC4 patrol, Xandren aware, others asleep.
Xandren gets his four hours, everyone else gets their six, and watch is covered.[/sblock]