Landscape texturing problem

Hi there!
I need to create a 10x10 km landscape using real elevation data. I have a satellite image of 20000x20000 pixels, which I want to use
as a color map. I use World Machine to cut my height map and the texture into 25 tiles each. For a height map the size of the tile is 1009x1009, and for the color map 4096x4096. Next, I create a master material, where I convert base color texture to a parameter (each tile I will assign an instance of this material with its own color map). After that, I import tiled landscape and assign instance material with its own texture to every piece. As a result, I get a large landscape covered with a satellite image. But there is a problem, between the pieces of landscape there are such seams, from which I can not get rid of.

How can I get rid of these seams?

May be for this task it is better not to use landscape, but a static mesh with lods?

But then I will lose such useful functions as landscape material and automatic vegetation …

I ask your help, maybe someone has already encountered such a problem.

A mandatory requirement is that a satellite image of high resolution be used as color map for terrain.

I hope for your help, thank you in advance!

This is very simple material with mapping scale set to landscape size