On the far right of the house, where you call the boat, there is a rock you can take a running jump to get up on to.

Once there nothing can get you, but smokers & hunters.

Wait till the 2nd tank music has ended and a survivor says the boats there.

Wait 5-10 seconds then run like fun to the pier/jetti.

Jobs a good 'un and you're sailing off into the distance waving goodbye to the horde.