Game update 1.2 required. Add 2 things to (path-to-game) folder: SoftTH (fullscreen, DX9 x86 game) & Widescreen Fix*. In game launcher, select base PLP resolution. All views good, though 3rd person has 2 issues: FOV bit strong; when nitro, image is inverted.
(PLP screenshot with bezel effect)
Download here: http://thirteenag.github.io/widescreen_fixes_pack#flatout & Note: FOV edit does not work
View guide for general help with the instructions.