What about a bit more emphasized: "I do neither have a wife nor children." ?
No, that doesn't work. Adding "do" here doesn't do anything for emphasis, it just makes the sentence wrong.
That doesn't work. When we use neither/nor and either/or, we need to use a parallel construction. In your suggested sentence, the construction is not parallel. Compare:
"I have neither a wife nor children." -- We are "equating" two things (wife vs. children).
"I neither have a wife, nor do I want one." -- We are "equating" two actions (having vs. wanting).
"I neither have a wife, nor children." -- The "equation" is flawed (having vs. children).