I shot a roll of PanF+, developed in Caffenol-C, then fixed for 3 days in a fix of 300g of Kosher salt in 1L water. It worked, the neg did clear (mostly), there is a little bit of base fog that does clear completely when a test part of the neg was put in a commercial fixer (Hypam), but I would say that a salt water fix does work if you have 3 days or so and have $ to spend on salt that is actually way more expensive than good ol' commercial grade fixed. A box of a Kosher salt was $4 for about 453g, so this is hardly a economical solution, but possible....

Neg scan of frame dev Caffenol-C and fixed in 300g Kosher salt to 1L distilled water for 3 days (this is not the frame I mention above that I subsequently put in Hypan):


I chose Kosher salt due to having no iodine as mentioned above by Rudeofus that too much iodine can adversely affect...