First I want to say this is such an amazing map. i love the design and effort you put into the map. I was so amazed by the design that i tried to make map for myself but was unable to figure the system. However my Idea was inspired by your map.

My Idea is the exact opposite where instead of a vast wild island it would be a 1 tile heavy urban environment with building on average being three or 4 stories tall. It would Be a QZ with concrete border walls, tight alleyways, and encouraged roof to roof access.

This is the lore I came up with.
"As Knox Event began to spreed, the government set up QZ all around Washington DC. Your QZ was one of the only place unaffected by the Knox infection. After about a year in the QZ all hell has broken loss. Somehow, the infection had breached the zone but you don;t know how as everyone in the city was immune to the airborne variant as tested at the beginning. Now you find your self in the ruins of the last bastion of Humanity."

Would this be a map you may be interested in making. I can easily see the cruise ship lore in Island Z making there way to the QZ when it sunk.

Thanks for reading
Yeti