this is what I’ve been doing for 70.3 and the associated training sessions
60-90g per hour of carbs. this is 240-360 kcal. I went with combination of clif bar and 5 gels diluted with H2O in a bottle for race; I only did the gels once before in training because I find it disgusting and otherwise go for clif bar and banana
from a cycling nutrition talk I took away that you should take in 30g carbs/hr for 1-2hr events, 30-60g for 2-3hr events and 90 for >3 hr, the reference given was Med Sci Sports Excer 41(3);709-31, 2009.
spread out well over each hour e.g. eat every 20 or 30 minutes
I add 0.5g himalaya salt (simple from grocery store) to 0.75-1L H2O for training and drink that within one hour (1L in 30°C otherwise a bit less depending on how I feel, I definitely do 500mL in cold conditions). if I have it around I add juice of half a lemon.
I have also used mineral tablets, felt good but they did not have enough sodium
my plan for this year is to improve my liquid nutrition, just ordered Xendurance Fuel-5 as per AACC podcast recommendation and will try to supplement the required salt in it. alternatively I have also ordered maltodextrin and flavodrops from myprotein as per @JulianM recommendation to try out mixing my own stuff (+ salt). side note, I will also add whey protein to this to try as my own recovery mix.
the key take away is to try it during training!