A single mesh in Poser can have multi-tile UV maps (known as UDIM), but it can't have multiple UV sets.

And no, subdividing won't distort the texture because the map still corresponds to the size and position of the base geometry. Stretching the geometry is what distorts the map.

Reduced to 104 polys:

SubD'd to 10.2mil in zbrush and sculpted/textured (5 min job):

With hard surface models its usually not necessary to keep all quads. Reducing to tris is usually more efficient. And because the surface isn't generally going to be deformed (like organic shapes - characters, clothing, etc), you don't have to worry so much about distortions caused by tris when the mesh is deformed.