Yo Reynolds, if you do choose the wyre forest, prop the best place to bivvy down for the night ( in oct) would be at goldilocks cottage. actual house is owned by the cabury family, and normaly boarded up like fork knox, but does have a nice wooden veranda ( spelling?) to doss down on. Would provide a bit more comfort /shelter for you.
As RD says, best stuff is via local knowledge but quite a few locals on here. Have got GPS routes if needed, but a rough namecheck of people to ask , RD, myself, MiltiantGraham.
As for doing 15 mile a day, appriecate you would be carrying own kit..but it’s not exactly pushing it..You could do an off road route of Clent to Kinver to Wyre then a quick loop of the forest. approx 35miles…just a thought.
Hope this helps..