Clean your mess
As a common courtesy you should pick up after your pet without being told to do so. As for using the fields etc., you have no knowledge who will follow in your path and step in your mess. Your logic in using those ‘out of the way’ places is flawed. Let me cite the sad and worsening state of our oceans. They have become huge floating garbage dumps and will continue to do so until the citizens of the world realize that those who follow behind us will step in our mess.