It's not impossible and players have done it since the 1970s. You simply ask what direction your character would go based on what they do know. However they made decisions about which direction to head prior to the player finding out that information, that's the same decision they should make now. So if they were using tracks to follow, or trying to keep below the hills to not be seen from afar, or staying on the hill to try and see ahead, or trying to stay out of difficult terrain, or avoiding areas where there could be an ambush, or all the things which go into overland travel - those are the same things they should use now.
This idea that you cannot separate player knowledge from character knowledge is absurd. It's a key element of role playing. You can do it to play an elf rather than the human you are, you can do it to play a spellcaster or sword fighter instead of whatever profession you are, why can't you do it to play a character who didn't see a map you as a player have seen?