I've seen up to 20 people in the Premiere Salon, spread between the restaurant (most tables occupied), the lounge part towards the right/back, 1-2 people in the work area, etc. This was for an 11am departure back in June, haven't been to the lounge since.
There is a protocol for letting people out, there in fact must be, to deal with cancelled departures. But doing it because a passenger is playing games with fake tickets will definitely lead to nasty looks. Nothing they can do about it, but it'll raise eyebrows.
Lastly, I don't get the point to book such a complicated ticket only to be in the P lounge. Of course, if one has to transfer and wait for a connecting plane anyway or if one is leaving from Paris anyway, then the P lounge is by far the very best way to spend that time. But to make it a destination in its own right? I fail to get it, it's just an airport lounge.