registration

I'm have been looking into registering my images for copyright and I understand that there are a couple of options in regards to whether they are 'Published' or 'Unpublished'. It seems to be a grey area whether sharing online is considered as Published. I'm still looking into this but so far...

How do you handle registration plates on cars? i find them really ugly most of the time but I don't have time to unscrew them all the time since i often switch location multiple times. How do you handle the plates? should i cover/remove them in photoshop? I want to hear all your ideas on how...