Three times recently I have encountered foreign traders while on a hunt, each time speaking with them and presumably telling them to wait a few hours and I would be back with the world's supply of quality furs.
Each time I have got home, loaded up on furs and headed back to where I met them. Each time it seems this group of six or seven Swedes crashing about in the undergrowth is far more elusive than any elk.
Foreign traders are combing the cuds looking for hunters like me. They have no reason to hide from anyone, and in fact would want to make their presence known to everyone possible. Maybe a chat option to tell them you'll be back, that makes them remain in place for a day? Or now that NPCs can light fires, make fires visible from a long distance away and have the traders make camp and keep a fire burning?
Even better, I would prefer to see foreign traders set up in villages for a week or so at a time. It makes no sense to have them wandering about randomly, they would go to a settlement and wait for the local hunters and trappers to come to them.