While I do believe that there is something fundamentally wrong with the current clutch modeling, I really don't see how people are having so much trouble with this. I raced last night and was able to finish 33 laps around Westhill and 25 laps around South City Classic in road cars with H-shifters. In both cases I finished the race with barely any heat at all in the clutch.
I honestly don't know how or why people are having such trouble with clutch overheating. Seriously - if you can't finish a race without burning up the clutch, even with the currently flawed modeling, you need to take a good hard look at your driving style.