Rob, I don't believe that functionality exists on the app, perhaps because it's quite complicated. For example, I don't believe it's possible to denote a VP as an overnight stop in the (Android) app.  

However, if you're not aware, if you have planned a route on the app, we have the option to select 'Save' and then 'Open on Web' to open that route directly on the website. Then we can easily split it into days. 

At the moment, I use splitting into days to split out sections that I might want to do on a train because I'm too damn old for them big hills.  But there's no way to mark that section as "not ridden" and keep its mileage and climbing out of the totals.  I know from experience that it is hard to tell what is hard and what is easy for any given piece of software - I just wondered if there was a way to exclude a section from the counts, but still keep it on the map.  It may already be there and I don't know!