Here is my FIX for the FOV no hack:
1. Load the game up
2. Switch to 1920x1080 apply
2b. Make sure you have all the visual setting to the way you want it after the fix you can not edit anything or you will have to re do all the steps
3. Go in to displays options and advanced where the FOV is supposed to be you will now see the FOV slider
4. Set the FOV to MAX and apply
4. Load a level play see that the FOV is maxed
5. Save and exit the game
6. go to C:\Users\[user name]\Documents\My Games\Far Cry 4\fb656277-0267-4dbd-b4ee-c634994fbfd8\ * should en this for everyone *
7. load GamerProfile.xml in text editor do a find on : ResolutionX and ResolutionY and set these to your multi screen resolution
ResolutionX="5760"
ResolutionY="1080"
Save the file
8. load GFXSettings.FarCry464.xml in a text editor
Look for the first part that has the <RESOLUTION node :
<EXECUTABLE Value="FarCry464" />
<EXECCMD Value="" />
</APPLICATION>
<GAMESETTINGS>
<RESOLUTION Width="5760" Height="1080" RefreshRate="60">
Change the With and Height to your multi screen resolution, use the same values you used in above ResolutionX and ResolutionY
9. Save the file
10. load up Far Cry 4 the FOV is fixed and play DO NOT go into the video opeions or it will revert everything.
hope this works for you guys.
EDIT: Sorry, didnt work. the FOV value used by Single Monitor resolution is bypassed totally in memory when multi-monitor resolutions is used.