Its rare to see a photo with the extra wiper motor visible as well as the wiper.
Experts I've consulted in the past seem to share the opinion that the 3rd, top-mounted wiper was hand-operated on the B20s that had them fitted. A wiper motor in the lower-roofed coupe would:
1. impair visibility
2. be a major cranial hazard in a crash
There is also the question of how the upper wiper would be synchronised with the standard ones...
The ex-Claes 1953 Liège-Rome-Liège rally-winning car has been restored with a motorised wiper. But one of its 60s custodians says it didn't have a motor when he had it.
A berlina roofline would make the motorised wiper more practical, or so Chiron thought, presumably! The question of synchronisation remains unanswered.
It look as if Chiron has a headrest on his seat, while his co-driver has a pillow!
Here's a photo of the interior of the Claes car (credit Will How):