I was looking through old posts and found a user asking about perspective configuration. What with the source code being released, I figured I would add this functionality in myself since there seemed to be no other way of doing it. Currently the function doesn't save between restarts of Penumbra, or even between the Main Menu -> game transition, but I'm working on it.
Image because I'm so damn proud of myself.
Code Here.
EDIT: Updated to save FoV settings to the settings file. (My code for the saving is a little sketch, but it seems to work.)
Update here.