Ask hm directly, why is everything in your girl's name? He must have bad credit, because that is what someone with bad credit will do. Ask what state he came from (nonchalantly, prior to asking him the first question). Get him talking, especially after he has a beer or two. He might even show his driver's license to you if he is really drunk, and you can finesse the situation to your advantage.
Do a record check from the last state he was in. Especially civil and criminal....dudes who get women to put things in their girl's names, are many times abusers and slicksters, with credit issues. Typically, their mommas were doing that for them. They also have get rich schemes that backfire, so they move around a lot to avoid being caught. And chances are he may have warrants for failing to appear---if he registers something in his name, the warrant will pop up, and he may be arrested.