This could be a mod of its own since it has nothing to do with weather but should be used in conjuction with Tedious Travel in my opinion.
This could be related to Speed and Agility bonus, and/or to athletic skills.able to pass through such terrain easily
This probably is the most difficult to translate into game mechanics.with little fear of getting lost
Lower chance of random encounters, for example.meeting the native monsters
You can become aware of point of interests from greater distance (but TT should interrupt travel).or missing places of interest.
All of this hoping you can add new advantages/disadvantages!