We dood the same WL thing at Lughead, but set the 0-0 WL some distance below the lowest part of the plane, usually the extended landing gear, so all measurements on the plane would be positive.
Knowing where 0-0 WL is then, the hardware can be checked in the hangar by locating the hangar floor in terms of WL.
Similarly for the fuselage stations, the 0-0 FS is set some distance ahead of the nose cone, so all dimensions on the plane will be positive when measuring the hardware as built.