I won it with 908, but you will need a careful babysitting, rocking Bob's and good luck to win it.
I had max aero and max power and then I added some ballast to meet PP limit. I did my stops on lap 3 for Inters and on lap 7 for Inters again. You have to keep your Bob hot and drop the level for corners where they usually crash (they've been discussed on other threads several times).
I had one Bob with level 40 and one with level 38. I always started with level 40 Bob but for some reason if I changed Bobs in every stop, the 40 level guy was terrible on second stint. So I drove two stints with him and then changed to a fresh guy on the lap 7 pit stop.
That is the basic idea, rest of it is a lot up to luck. You need to make your way up before lap 7 so that you are close to top runners. When you go to pits, it's up to the group, if they keep themselves hot or not. If they drop down to cool, then when you come out from the pits and start pushing your Bob he will gain enough time to overtake the leader when he pits on lap 9. You also need to have big enough gap when he comes out of the pit, so that his level will drop to cool. If he gets into hot zone and on your Bob's draft its game over.
I had several attempts on this, first when I got close was 2nd place with 2,3s to leader. Once I was making big enough gap after second pit stop but then my Bob crashed. Then I got really lucky, when the R8 went off on first lap. So the battle was against Bentley and it was easy to beat compared to R8. So it can be done, but I feel it's mainly up to luck, how hot top AI's keep themselves. If R8 gets a good partner to push him faster it seems impossible to win with the 908.