Depends on the insurance requirements and what the guy is all about. If the insurance has no requirement other than that you be there, and this guy just wants to use you for that, you will be getting paid to pick your nose and speak up if your ticket is in jeopardy. Hopefully the guy's fun to hang out with.

If the insurance has "IOE Like" requirements, then you might have to accomplish certain tasks, instrument approaches etc.

If the owner is looking to you to have a plan to actually improve his skills, then revert to CFI-mode and come up with something similar to the CPL dual program (various XC flights, IFR/VFR, whatever maneuvers are safe to do in the actual airplane, short LDGs, etc).

For liability purposes, I would not volunteer to enter dual-given in his logbook if you can avoid it.