Glad to hear that you’re happy with the watermask and the TrueSky compatibility update!
We would certainly like to add terrain editing in the future. However, it may be a while before we are able to look into properly implementing that feature. In the meantime, if collision is not an issue, you may be able to modify the water material to lower the world position of tile vertices within the watermask.
The current Exclusion Zones feature is experimental and temporary, and may not work like you’re expecting. However, if you want to use it, add an element to the Exclusion Zones array. The South and North variables are for latitude, and the West and East variables are for longitude. Think of the Exclusion Zone as a rectangle with sides at these longitude and latitude boundaries - any tile inside this rectangle will be culled.
The easiest way to find the values for the exclusion zone may be to create an actor and add a Georeference Component, then move it around the map to figure out where your latitude and longitude boundaries should be.
Stay tuned for improvements to tile exclusion in the future!