Remember also that a DIYxGPS 600 can also be used to get your SR.
It has some practical points too...
Generally I would recommend designing a route with two different loops, both of which start from home.
That way your sleep stop can be in your own bed, with your own shower if needed, and limitless changes of clothing, easiest feeding, (favourite meal in fridge), and not forgetting things like floor pump, extra tubes, and even in extremis the ability to use different bike on day two.
As Feanor said, make the first control on day two a 'long' one, and as you design the route, make it as flat as possible, or even downhill if you live up on some moors, and if you are really clever plan routes that go in different directions and just before you start, choose a tailwind assisted day two start....