Hi phileas
I'm walking the Cornish coast path but unfortunately I haven't walked that section yet
I wild camp in the woods, I work out how many miles I want to walk with the distance finder on the swcp web site, then go on google maps to find a suitable location, usually a small wood in a valley.
If you look at port gaverne there's some Heath land up the valley that looks like a pretty good site ( not that I would condone such behaviour of course, wild camping is technically illegal)
I've never had any trouble wild camping but remember camp late, break early, and leave no trace