I recently had a Discussion about 19F NMR referencing with a fellow PhD student. Apparantly, it's a pain if you want to be able to compare different measurements or use it in a similar way to chemical shifts in 1H or 13C NMR. As far as I know, the shifts are also extremly solvent dependent. Bottom line what I would do: just describe what you have done and how or if you referenced your spectra. Then wait until someone figures out something meaningful and practically doable.
I didnt know this effect was so powerful. I guess thats why people run the spectrum in CFCl
3 when they need to reference. Since its the solvent, it will have a stable shift due it its very high concentration.