You're better off in a campsite, from the point of view of security and your own personal safety. The few Euro you pay overnight is worth the peace of mind, I think.
You can no longer just camp in fields - certainly not without asking the owner for permission first. Landowners are not liable if anything happens to you.
If you just set up camp in a field and suddenly find yourself surrounded by curious cows, or set upon by a bull - far more dangerous than you might think - you have no-one to blame but yourself.
