In English, it's best to remove redundancy. This means, try not to say the same thing twice. You should say "just you" or "only you".

Just you is one way of saying it. This does change with different countries though. "Just you" in US would be fine but in some other countries, it would benefit you to add salutations. Cultures differ and so does the way you can say things. Even in some English speaking countries, it matters a lot.

I think that that is something that would be heard in spoken English. I don't think you would write it like that.