I use solar salt for water softeners when transporting fish. For what to use, that all depends on the amount of fish to be transported at once (pounds). To be on the safe side, plan on 1/2 pound max per gallon of water and use pure O2 for an Oxygen source.
I cannot give you any advice on transporting fish without using Pure O2 (like O2 you would use for brazing or cutting steel).
I have transported some BG in a 120 qt cooler just by using a bilge pump and a spray bar that sprayed the recirculated water down into the cooler, but that was an hour tops drive.
