Hi Lucien,
This will absolutely no use to you whatsoever, but about 7 years ago I had the chance to do a stretch of the SWCR. I caught the train to Plymouth, then my plan was to cycle to Mevagissey. I then found the track which was along the cliff edge, and impossible to cycle, me not being Danny Macaskil.
I decided to road – cycle the majority of the way instead. Still had good fun though, passing Looe, Polperro and Fowey. As I said no use to you, but enjoy yourself anyway.