This should be a good discussion.

My suggestions are
1. A moat made up of Weber grill burners. Anyone trys to get accross,
you instantly BBQ there ass.
2. Rifle tower, lots of amunition. (5 bullets for each member of
surrounding population)
3. two of each animal to restart population. (preferably opposite
gender).
4. Tele-porter to escape. If you go with a tunnel, it would be
flooded. If you go jet pack, the guy across in his castle will snipe
you from his rifle tower. (Check e-bay for a cheap teleporter.)
5. Seperate ecosystem/ oxygen supply - As ecoli and other diseases
break out, you don't want to be breathing this stuff.

I like the three little pigs idea.
Make sure you don't talk to the first two.