Landscape size: Need advice

Hi guys,

i m new in UE4 and i would like to ask for a bit help. I 've checked some tutorials and of course the tutorial World Machine to UE4 using World Composition.
Still, i failed to figure out some things regarding scales or better to say i failed to make it look good as much as i would like to.

What i m trying to achieve is to have around 1600 km x 1600 km real life map, scaled so that in resolution 1920x1080 player can see around 15x10 km of that map (that would be his max zoom) with of course zooming out to full map in different (simplified) LOD. The intent of this map is just to be one level for overview of where player is.
For more zooming (and other heightmaps) there will be other levels with more details for it, for example for inside town etc.

For heightmap, i m using World Machine and exporting as in that tutorial, so:

  1. heightmap imported in WM is 8068x8068 as tiff file
  2. area in WM is set to 1600m x 1600m as well as imported tiff heightmap (in File Input node)
  3. height for maximum 2100m and in File Input node is set to 1800m
  4. Exporting resulting WM file as tiled with 2017x2017 tile resolution, 4x4 tiles per side, blending 100 (which gives final resolution of again 8068x8068 in total of 16 files .r16)
  5. Switched to World Composition in UE4, imported r16 files by Import Tiled Landscape
  6. I ve used 16x16 components with 2x2 sections and 63x63 quads

And here my dilemma starts:
X, Y are set 100% which under shows 16-2017x2017tiles, 8.068x8.068 landscape
Z 1,758 instead 100 and i use logic: this 8km is some 200 times smaller then those 1600, so if Z in WM is 1800/200 = 9, times those suggested 0.1953125 gives that 1,758
Wold to meters is 5000.

So, what you would suggest as the best in terms of visual and performance to use for this kind of map? To looks good but still to not be to heavy on PC performance output, having in mind that this is overview level (map)? Am I doing something wrong with settings above?
Sorry for wall of text.