In addition to the anti-greifing features I see listed above, I have an idea.
How about something like a "push mute" (not a good name for it, but hopefully that gives you the idea)? Just like you can Mute any player so that you can't hear them, the idea is an option to stop a person or any object they own from pushing you. This would help people even if they are not on land they own.
For example: if someone "orbited" me I could then set the anti-push flag for that player so it can't happen again. Or, if someone threatens to push you, then you could set the no-push flag for them ahead of time.
By doing it on a person-by-person basis you don't have to turn off being pushed by everyone (sometimes you want to be pushed (as on a fun "ride" that someone has set up)).
You could make it so the flag won't stop a landowner from always being able to push a person who is on their land. (As for non-safe areas, maybe it would be turned off, but I'm not sure the best idea for combat areas.)
Anyways, just an idea I had. Maybe it has some side-effects I hadn't thought of that would make it unworkable, but I wanted to submit it for consideration.
Thanks.