Making a sustained high intensity effort for 4-5 hours is not easy to do when you're in a full body suit that prevents you from cooling off. The only types of

Making a sustained high intensity effort for 4-5 hours is not easy to do when you're in a full body suit that prevents you from cooling off. The only types of race in which they use something close to what you're suggesting, where the aerodynamic gain of the suit is higher than the danger to overheat the rider, are time-trials, or velodrome races, which have a lower duration (max 1h).