Was this the episode where someone asked how people fuel for long rides without needing to stop and refill with bags of mixes or carrying 50 gels? I think so.
If so, I think the hosts missed the easiest solution…
You carry two 1 liter bottles, each with 200g of carbs in them (800 calories each). 2:1 maltodextrin to fructose mix, with added flavoring and some salt. Then put either an additional water bottle or a soft flask of water in one of your back pockets. One direction/salomon make them for trail running that are easy to find. Somewhere between 500ml and 1 liter worth.
That gets me ~4 hours without stopping (400 calories & 100g carb per hour), while being sufficiently fueled/hydrated the whole way and not needing to stop at gas stations or open containers or whatever, and malto/fructose is super cheap. The one liter bottles are pretty darn sweet nectar, so having a third bottle that’s just water to have every now and then to wash your mouth/teeth out is ideal. If you want to get to 120g of carbs/hr, then supplement with a gel an hour or gummy bears or some other food.
Another option is using a wolftooth b-rad bracket to add an extra bottle mount on your top tube or downtube.