http://bearbonesbikepacking.co.uk/phpBB3/viewtopic.php?f=10&t=3105
Some links in here that may be useful, more for MTB routes but a few places that list easy traffic-free routes, cycle routes and Euro route-finder sites that come with recommendations. If you find anything new + useful pls post it up here or on there.
I’ve done a few similar road trips with anything from a small rucsac for B+B tours to a bikepacking set up for wild camping. If you’re taking a rucsac it may be worth considering a small frame or seat pack to take some of the weight, or pack really light (<10lbs or so).
I’ve never needed to book accommodation in Europe, occasionally had to try 2 or 3 places to get a room but that was the Alps when the TDF was passing. B+B touring can be kept pretty open-schedule, just aim to be in a town between 4 and 6pm.
And make it 5 days if you can .. or 6-7 : ) takes me 2-3 to really get free of the daily stuff and settle in and time pressure can kill the experience.