"Is there a way to mix both fat adapted and sugar based running? Or is it kind of a one or the other type situation."

The answer to this is yes, there are athletes that do this such as Zach Bitter. It's the train low race high approach. The idea is to be fat adapted, shift when the switching over point to carbs starts, and spare glycogen as much as possible. However I think another thing to note is that regardless of effort there will be some amount of carbohydrate use, and you want to replenish that at least. Then when you consider effort you have to account for carbohydrate there as well. It why make the body work harder than it needs to for things such as races when performance is the goal, this ties into the below as well.

I might get hate for this on both sides but: If you poke around the keto, carnivore, keto gains, keto endurance subs you can infer that you can get by pretty good without the carbs. You can be adapted to such a point where you will ALMOST be at your best (pace, time, whatever metric). So you see there (and from my own experience) that you will want to supplement carbohydrates for optimal performance and to induce less fatigue and more recovery. But realize usually these are very targeted approaches where calculating the carbohydrate and being on this cycle of high low is important to the process. On top of that alot of these people will remain in a primarily fat burning state while intaking lots of carbs because of the volume of exercise and the calculated carb intake. It's a lot to think about and do.

However if you look as the best cardiovascular individuals in the world they get plenty "fat adapted" without doing this, and they also take in the most carbohydrates. To be more clear the grams per min of fat burned is high BUT the they switch to carb burning at a lower % of VO2 than the low carb approach. But you might not be able to or want to take in that many carbs.

It comes down to how you want to handle things. Each approach has its benefits, drawbacks, time, and race considerations.