We have noticed that there is little information on this topic so we have created a very simple tutorial and plugin for accessing and modifying the LocalPlayer camera projection matrices.
You can check it out here: http://www.geodesic.games/2019/03/27/projection-matrices-in-unreal-engine/
You can download the plugin here: GitHub - GeodesicGames/SimpleOffAxisProjection: Simple plugin for modifying local player projection in UE4
Hope this helps you guys out. If you have any questions feel free to ask us on our discord channel.