The TF 51 is a P51D which is a civilian rated Airplane (i think!). The TF51 has no fuselage fueltank, it dosent have any steelplates for armor at all. It does have a second seat where the fuselage tank would be.
Would be neat to remove that plate anyway, but its not correct in terms of history.
And messing with the gamefiles would probably work in singleplayer, but multyplayer would be a nono because intergrety check.