Joe,
Your observations track mine. Little higher discrimination and a little lower sensitivity gets things about as good as I've found over the wet salt.
Most places I've used the Tejon or other detectors that would not ground balance to the wet salt, the best I do is when I ground balance to the nearby dry sand, increase the discrimination, like you say, to low to mid side of foil, and then if needed, turn the sensitivity down a little. If I try to take the ground balance all the way to the end of the adjustment, I usually get falsing that I don't get when I balance to the nearby dry sand.
Down side is that some rings or small jewelry I've found or tested, are in that foil range that I've now discriminated out to handle the salt.
I like a smaller coil better over the wet salt; can get away with a little less discrimination and a bit more sensitivity; but I like the 3.6 x 18 inch clean sweep over the dry.
tvr