Of course you can operate and operate well on a high fat ketogenic diet. This research study explains that it is perfectly possible and natural - eskimos did it well - to operate at a high level on a high fat moderate protein and low carbohydrate diet. Read the whole study - it is excellent. Here is the abstract to whet your appetite:
Impaired physical performance is a common but not obligate result of a low carbohydrate diet. Lessons from traditional Inuit culture indicate that time for adaptation, optimized sodium and potassium nutriture, and constraint of protein to 15–25 % of daily energy expenditure allow unimpaired endurance performance despite nutritional ketosis.
It is also interesting to read how Mark Twight - the top alpinist - applies this principle.