I made a small mod that enables "5DOF" (yaw, pitch, X, Y, Z) TrackIR axes in LFS. It modifies the custom view parameters in real time so it is a bit 'hacky', but it seems to work quite well for me. Requies TrackIR with vector expansion.
Made a minor update (v1.1), it adds a setting for automatically shifting the view on the X axis with head rotation, so you can look over your shoulder simply by turning your head... I think it should also work for people with no vector expansion. (Assuming the whole thing works for anyone else but me )