One other thing to think about is how will the truck be used. Mine is garaged and used only on nice days so I don't drive it in the rain or snow. Slide underneath and it looks like a brand new truck. So I used approach #2 and carefully repaired and coated everything I replaced. It is not really ever going to rust since the only water it see's is in washing it. Now if it was a daily driver I would really have focused some time on the historic rust areas knowing that they build-up mud, leaves, drain holes get plugged, road salt or gravel (which sandblasts undercoat and paint off) etc.
