The way my SkyLands work is vastly Different from the way SkyLands are usually made.
Basically, my SkyLands are normal Terrain with the Bottom cut away.
This is much more work than it Seems.
To get the "Smooth" or "Cool" underside of the Terrain, aswell as give bigger Islands a more natural depth, I added a kind of Border Biomes.
That means each Biome consists of actually 10 Biomes. From OuterMost, to InnerMost. Each Biome is about 10-16 Blocks in size.
That means, my CHC settings are Vastly Different from yours. For Example, the Biomes furthest away from the Island Border use these Settings:
CustomHeightControl: -35000.0, -30000.0, -25000.0, -17500.0, -15000.0, -7500.0, 175.0, 250.0, 175.0, 250.0, 175.0, 250.0, 175.0, 250.0, 175.0, 125.0, -25.0, 0.0, 0.0, -25.0, 0.0, 0.0, -25.0, 0.0, 0.0, -25.0, 0.0, 0.0, -25.0, 0.0, 0.0, 0.0, 0.0
The Biomes at the Border use these:
CustomHeightControl: -50000.0, -50000.0, -45000.0, -40000.0, -35000.0, -30000.0, -27500.0, -25000.0, -22500.0, -20000.0, -17500.0, -15000.0, -7500.0, -3000.0, -950.0, 175.0, -25.0, 0.0, 0.0, -25.0, 0.0, 0.0, -25.0, 0.0, 0.0, -25.0, 0.0, 0.0, -25.0, 0.0, 0.0, 0.0, 0.0
Because I dont use "DisableBiomeHeight" I dont need to limit Terrain above the Actual Islands. That way I can have Hills on my Islands.
The Downside to this Approach, is as I said it takes a Massive amount of work to get any Result.
For Example, to get only a circular Island like this:
It takes 10 Biomes working Correctly. Because from the outer edge to the center it needs different Thickness of the Island. Its hard to Explain, but if you take a Look here:
(From further down the Thread)
This would be a normal BiomeMap, (Each Color Represents a Biome)
To work with my SkyLands this needs to be this:
It is basically the same. But if you look closely each Island is "darker" becaus, it actually Multiplies the Biomes by 10, as each Island changes the Biomes to the Middle. (Each Color, or Darker variation of the Color is still one biome)
This world consists out of 302 Unique Biome files. (Not Actual Biomes in Playing sense, but technical each is a different Biome).
How I managed to draw a BiomeMap is explained further down in the Thread.
If you wish to pursue this Approach, I can help you further along. (even though I doubt it)
The Downside is, that unless you integrate Object Islands, and even mor Complicated Biome Magic you only have one Surface Height for the Islands.
As for the Streams/Rivers:
They work with the: "Surface and Ground control" in the Biome.
These are the settings from my Plains Biome. If you wish to make more Biomes, with these little Rivers, you will have to use the same/similar values for each biome, so the Streams link up.