Here's another great seed for Minecraft 1.11.2 where players start off on a sand barge with three trees and a small amount of dirt. This will be one difficult island to survive on, but definitely not impossible!

The seed is: -9205151696820667704

While this isn't the easiest island to survive on, it's definitely possible. Consider spreading out the dirt and growing a forest for apples. There are other Minecraft islands nearby for the more faint of heart. It's easily possible to just swim over to other islands and escape the perils of the 1.11.2 survival island seed for Minecraft.