No need for carbs once you’re fat adapted. (But for a 5 or 10k most carb eaters don’t need that many carbs either). Trust the process. I can run a full marathon on just water and salts. You’ll be fine. If you do need a little boost I recommend adding MCT oil in coffee about an hour before you run (but build up usage slowly).
Carbs will spike insulin which will block access to fat stores. If you wish to burn fat, keep the insulin level low. I train in the fasted state. Over time, I have been able to run for 2 hours with literally no food. It took me some time to build up to do this. It doesn’t happen overnight.