uv mapping – efficient development in a multiple hard edge object

I am having problems to develop this without creating hundreds of seams that greatly increase the count of vertices in the game engine (Unit).

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I have tried the various methods of projection without much success. Three flat maps (45 degrees looking down, 45 up and one side) threw the remaining amount, but still dozens.

I've tried all kinds of manual sewing drawings, but I can not figure out which would be optimal, so I'm looking for suggestions.

As for the texture that has contiguous seams it really does not matter.

Cross published in Blender Stack Exchange