If it’s really just 2 titles and only 1 needs re/writing or adjusting, then I suggest you do the writing at runtime.
There was recently a somewhat objectionable post where some c++ was shared to alter the landscape terrain at runtime.
Your situation is unique enough that you could make use of this without suffering performance costs.
As a general rule I have to disagree with it, since making your own analaitical mesh out of the same texture is just overall better for performance.
But if you dont want to mess around with that, this one particular case may just be able to swing it.
All you really need to change is the Edge pixel of the next adjacent tile to get it running without seams.
Further, you can actually levarage the pixel calculations of the next adjacent pixel strip to make sure the terrain is accessible / potentially create a pathway if needed.
All at runtime… without a procedural mesh component and loads of tris math…