I like @Twowkg’s idea.
You just need to be consistent with your fueling (both frequency and type of fuel you’re using).
Fuel the work you’re doing, and find a brand that works for you. What have you used in the past?
Once you start consistently fueling your rides with something that works well for you, you’ll be able to increase the amounts you take in over time. Start somewhere low, around 60g/hour for a week or two, and then bump up to 80 before getting to 100.
Drink mix is the best way I’ve found to keep a solid flow of carbs going without an upset stomach. Some gels are far too thick/rich for me, and they need to be consumed with water, which at that point, makes me ask, why not drink the carbs to begin with?