I know that practicing law without a license (in the sense of pretending to be a lawyer and helping other people do legal things) is illegal. I also vaguely remember hearing that threatening to sue someone unless they pay you can be extortion, and thus illegal. And sending false or misleading mail through USPS could conceivably be mail fraud.

But say I have a dispute with someone--either a disagreement over the interpretation of a contract, or a situation where I think they owe me money and they aren't paying.

I could just go sue them in small claims, or proper court if the amount is large enough.

Presumably I could write them a personal letter, saying "Dear X, because you owe me $XXX.XX, I will be suing you.".

Can I write a similar letter, but make it up to look professional and sign it in the name of a fictitious lawyer? Not a threat, but a bluff that says I am going to sue them and have hired Fakey McLawyerson to do it. If they still don't pay up, presumably the next step would be to hire a non-fake lawyer to actually file a suit (or do it myself in small claims).

How many laws would such a scheme be breaking?