Option 3 is what I'm looking for but if you are working on something related to this I'd be glad to wait

Just let me know once u'r finished
Btw shouldn't it be possible to make some kind of invisible wall that still allows players to walk over it but blocks monsters like protection zones. So instead of making monsters allow to walk only certain sqm's we could try something with invisible borders? Just an idea ofc
Or invisible furniture but this would only work for lesser creatures which can be trapped.