At least trying pickle juice for muscle cramping should not do any harm:
"At these volumes [3 ounces], ingestion of pickle juice and CHO-e drink did not cause substantial changes in plasma electrolyte concentrations, plasma osmolality, or plasma volume in rested, euhydrated men. Concern that ingesting these volumes of pickle juice might exacerbate an athlete's risk of dehydration-induced hypertonicity may be unwarranted."
(Notice the small volume - only 3 ounces - that seemed to relieve the cramp.
Thus, there are not studies that I am aware of that speaks to the "safety" of large volumes of pickle juice.)