I never did anything fancy with my bases, one at spawn and one next to the mine.
I take it that your "sky" & "sea" base concept are focused on forcing raids into a single point of approach? similar to 7 days to die.
nah, its more like building stairs and set ur base higher than surface of the sea.
No raid occurred because (usually these reason)
・The location where the raiders appeared cannot be found on the screen, not on the minimap. (The raid target was surrounded by sea or the terrain is uneven.)
・There are many items that reduce the number of attackers, and the number of attackers is below 0.
・The raiders are being blocked by invisible wall
・The raid target was standing high on a platform, inside a building or a platform on the sea
There are possibilities like this.