There is a lot of debate as to whether supplementing salt/electrolytes beyond food and something like tailwind or Gatorade is needed at all. You can do sweat tests to see what volume of water you need to replace and precision hydration will check the salt volume in your sweat (for a modest fee) if you are curious. (How much you sweat and how much salt is in that sweat are two entirely different things I have found.)
I have found itās not necessary to delve into the supplements of any type until Iām shooting for the marathon distance. (There is an invisible wall out there at 18 to 20 miles in my experience.) Beyond that distance, I have both over and under shot on the salt amount and caused myself problems both ways.
Personally, at anything half marathon or less water with a good breakfast like a bagel or peanut butter tortilla (or something like a cliff bar) would be enough for the race without putting extras on top of that. Have some of the Gatorade at the aid station if you want to.