How NOT to plow neighbor's fields...

[crashtestdummy]

So, when plowing my own fields, I noticed the Y key cycles between allowing the plow to plow an existing field and creating new ones. Is there not an option to keep the plow from affecting unowned fields and only plow my own fields? I don't know how to reverse with a trailer to save my on butt and my workaround is to flip u-turns at the end of a field to line up the other way, but my neighbor's fields are turning into a mess because I try not to just stop completely each time to raise and lower the plow...time is money, but I don't want to piss off other farm owners either.

[Flamenco]

You could prevent this from happening by circling your field with the plow first, thus keeping clear from any adjacent field.

[Tankfriend]

I don't think there is such a setting or mod. Frankly, the AI farmers don't care, though. If you personally feel disgusted by the destroyed AI fields, then you'll sadly have to take the time it needs to raise / lower the plow.
Alternatively, make the turns on your field early enough so you don't move into adjacent AI fields, and then work the borders of your fields more carefully later to clean everything up.

Originally posted by crashtestdummy:

I don't know how to reverse with a trailer to save my on butt

If you have trouble precisely moving and parking trailers by reversing, then try flipping things around and connecting the trailers to the front of your tractor instead (provided your tractor has the right trailer coupling up front).
Driving forwards instead of reversing, it's often much easier to handle trailers - especially if they have a steering axle of their own.