Problems with lightmaps on long meshes

Hello to all. There is a problem with baking light maps. How to unwrap a long object correctly? How to pack so that there would be no empty space? I tried to cut a long piece and set it exactly in pixels, but this did not give good results. The seams remain visible, but if you expand it in a large piece, then there are no seams, but because of this there is empty space. I set the texel density equal to other pieces.
Even a plain cut in half is not baked seamlessly. is it even possible?