Arnage is do-able on a push bike, 20 minutes, we did that at the Classic.
Although you could be made to do a the long return leg if les flics are enforcing the one way system. I have seen pushbikes being prevented from riding against the flow of traffic.
Mulsanne is a very long pedal, would never attempt it, miss to much of the race.
Easiest and best option is a motorbike.