Structures can be built on top of rail signals. In order to make them placeable on water, you set the big electric pole to collision mask "object-layer" and the rail signals to collision mask "rail-layer". But this means that you can now build just about any structure on top of a rail signal, which seems weird. Is there any reason you couldn't make the rail signals collision mask be rail layer AND object layer, so it's still placeable on water but can't overlap with structures like in vanilla?
