Realistic? Definitely. I'm starting my first tour this Thursday morning. If I can do it anyone can so get planning.
Every last drop of advice you'll ever need is covered in this forum (admittedly it takes a while to find it all), the Travelling Two book and site and general tinterweb.
Dunno about prevailing wind direction. I have a 20 mile loop I like to ride regularly but every time I do it, I somehow have a headwind on both the outbound and return journeys. Go figure.