Rohloff_Brompton_Rider
Formerly just_fixed
i'm a reasonably unfit 40 year old fat bloke. it took me 10 hours. the last 3 were hell as i had blown. if your lad has exceptional grit and determination he should manage it in a long hard day. but he would be miserable and needs to be with a good rider who knows it (the route) well, for bail out options, accidents etc etc. however as others have said, split it, i would say into 3 days. there are many many good b&b's on the route. the best websites for accommodation are equestrian type sites as they tend to split it in to 3 days.