Carrying a scout (random 50 char) trough the dungeons is important yeah. You
must check everywhere you're going with your pvm, even in advanced frigost areas.
The disadvantage of this :
If "they" know the whois of your scout, they just have to add it as ennemy and check if it's connected to know that you're going to frigost -> probably to the next frigost dungeon that you haven't done yet.
To avoid this : create a new unspotted account and create a random character that you never invite in any guild.
Never go on the same map of your team with this char.
Do the dungeons with this char, and avoid being seen doing those dungeons with this "new" char.
Even if you do this, you should really get on 2 map on advance.
As an exemple of the psychotic paranoïa that you should apply to yourself : here is a configuration that seems good to me (you can be helped by a friend about the check on the bottom right)