Hi Syrous,

Camping in the wild in Germany is in most bundeslaender (provinces) forbidden or the rules are unclear. But if you ask somebody or camp on some empty feelds in the forest it´s no problem most of the time. Just pitch your tent when the sun is setting or just after dark and keep a low profile (no fire, torch etc).

In the Netherlands wild camping will be more difficult as especially the west is densily populated. Bu then again, we have LOTS of campingplaces (http://www.anwb.nl/ig/verblijven/campings/home.jsf , in dutch). To use this search type your destination under the 'Zoek een camping' box.
But if you ask a farmer they will most of the time allow you to stay on their fields.

Going alone is no problem as the countries are safe and you´ll most likely meet some travel cyclist on the way.

54 days should be enough depending on what you want to see and your way of traveling. How many days is an EU visa valid?

Cycle the world,
Marc