ease into reducing carbs and go truly aerobic
I typically train fasted and only add modest calories from a variety of sources when going beyond two hours on the bike. I didn't used to and the transition away from gels, chews, liquid food, etc. every 30 minutes or more was slow and purposeful.
In my pre-primal/paleo days I was "almost" fasted for most events (ie. no food until just before the start and then I would have a gel). Today I still don't purposely eat before working out or events; that said, I typically eat whenever I want to (2 to 4 meals a day; 18 hour IF when it happens not on a schedule) so if I eat before a workout, it is just because that is when I was ready to eat.
My typical day has morphed to 25 to 100 grams of carbs over the last couple of years and I don't do much adjusting for days with longer workouts (more calories but do not focus on just carbs). If I do eat on a longer workout I will choose things like Justin's nut butters (not peanut) and foil pouches of simple baby food (squashes, sweet potato, etc).
I think there are two reasons I use very many calories and do not "need" carbs all the time when working out. First, I have slowly adjusted to it and didn't sweat it when things didn't go as planned (I still carry a gel or two "just in case"). Second, I focus on my aerobic engine which is much more likely to burn fat as fuel all day long. Although I do not like HR, power and other sports formulas (it is a rare person that perfectly fits into a prescribed percentage of this or that) the formula most likely to slow you down are Mark Allen's and Phil Maffetone's (Maffetone used to coach Mark Allen). Ask Coach Google about either of these gentlemen, heart rate and 180 and start reading. It will seem to most that you are going painfully slow, but with time (months, not days) you will be much faster at a lower HR and burning fat all the time. There are some coaches and testing methods (not lactate threshold) that are able to test individuals and guide them to specific HR zones for the individual (not formulas), but as a starting point the Maffetone/Allen approach is a good place to start to get truly aerobic (and, back to the original posting, away from chronic cardio).