The same way that you need a skill at a particular % to do a quest the same way quests could be developed that require outdoorsman.
the easiest and simplest way to do that is that the NPC would give you the coordinates "deep within the desert lie a hidden trove of forgotten technolodgy. Noone knows where it is, the only indication is this old page from the diary of an army colonel. It mentions how they mastered some form of mechanised monstrocity and then set forth to defend a now ruined city. On the way they were ambused and completely annihilated. He goes on to include some cryptic numbers 87:63 but noone has deciphered their meaning".
So the PC has to essentially go to the coordinates, fight some monsters or mutants and get a reward of some sort. Or even better have him return to the quest giver and receive a reward from him.