You know, I probably worded that terribly. I'm using UDK. I know I can use decals or a plane to get it in there. I do appreciate your comment, though. The core of what I wanted to know is about the sizing of the texture. Is my logic screwed up when I'm thinking this out?
You do know that textures don't need to be perfect squares, right? You can just make a texture with 4096*2048 if you'd need it and there would be no stretching. Another solution would be to just make two big sign decals on the same texture and you could still have a perfectly square texture if you really want to.