Surely you folks aren't quite thinking in the terms that the programme normally does.
The couple of episodes I've seen take somebody (usually) with only a nodding acquaintance with the subject and make them appear to be a professional. (Turning somebody who ran a burger van into a Chef-du-Cuisine was a good example.)
Being consistent with that would perhaps be taking a low hour hobby PPL / glider pilot (even an aeromodeller) and trying to pass them off as an airline co-pilot / test pilot / other piloting professional.
Two obvious ways then spring to mind that could be used for the "assessment" part of the programme. If they were trying to bluff it as an airline captain, make them turn up and pass a typical sim-check. If they were trying to bluff it as a TP, have them fly an assessment of a new type with a safety pilot in the RH seat (and flying as Captain) to keep them out of trouble (this happens all the time in the real world) then give a formal debrief on the type to an audience of professional TPs and Engineers - again a real-world task that could be done legally and safely.
Could be quite fun, particularly since you'd not struggle to find a sufficiently loud and opinionated personality amongst the ranks of most clubs PPLs
G
Not a low-hour PPL, but helped put one of the Scrapheap flying-machine programmes together, and think this could be quite fun too.