SAFD: I went vegan in 2018 in part because of my GI upset on long runs and it has helped tremendously! I try to stick to some combo of rice/veggies/tofu the night before a long run. We will be eating at the Skipper Canteen the night before the marathon.
Race morning is a Clif bar and some coffee.
I don't carb load per say, as too much gluten is no bueno for me, but I try to eat rice and starchy veggies the day before a long run.