This is the most zombie ready house I've seen to date.

I call shotgun in my hands for when zombies attack.

I call shotgun, to make sure I get whatever room I want.

That person is going to die. It's a 100+ foot drop.
It's 'shopped.

Probably, but still cool... and not outside the realm of possibilities in all honesty.

The trouble is, is that depending on the zombie subgenre, an island can turn out to be a death trap.
The classic Romero Somnambulist zombies could just walk right across the bottom of the water and come up anywhere on the shoreline. This would present a similar problem to securing a land based perimeter, with the added complication of reduced visibility and diminished warning time... possibly cutting you off from escape.
An island in a swiftly moving river could work, but is unlikely to be of significant size and would also be a hazard to you.

At least this guy has a plan, what do you have