Hmm, wonder what would happen if I landed cos my cowling 'came loose'?
You would have to contact the Dutch equivalent to the AAIB who if they genuinely thought that all was cosher may give you permission to take off again.
Every landing with a powered aircraft (even a non self launching motorglider is powered for this discussion) other than in on a designated field is deemed to be an emergency and would normally attract the attention of the local constabulary who would pretty automatically contact the Dutch CAA etc etc etc.
In short I dont think it would be worth the hassle.
If you are serious about trying to land in your mates field the following needs to happen.
1. Your friend needs to give you permission
2. The local council (and more precisely the local Mayor) will have to give permission with that you
3. Contact the CAA who may grant permission.
This can be granted for certain occasions but dont hold your breath.
Dont think the Dutch authorities are as laid back as the proverbial Dutch attitude is supposed to be.
Actually my wife thinks that the Dutch are an uptight lot but then she is married to me!
FD