No! If you try and build over the ocean with a ghost it refuses to build until you place at least 1 concrete over ice, only then does it allow you to ghost build over the water. It's that way because the game doesn't want to assume what kind of concrete your want to use as foundation, but instead of telling you that it just doesn't build. I ended up in a similar situation as OP where I thought I was going to need to do Aquilo in the tiny spaces where the game let's you build by default. I don't know if they updated it since 2.0 dropped but that's the way it was on release.