I think you should get some fencing done ASAP to avoid boundary disputes in the future. If a small tree is growing on the boundary, which side of it marks the boundary when it has grown in diameter, for example?
I doubt anyone is really going to moan too much for a few inches or even feet either way
But would be fairly cheap/simple to run a demarkation fence round ur boundry, can be anything from single plain wire even used blue poly prop rope on 1 job and just enough posts to hold it up, mibee cut a ride round the boundry too, infact a ride would probably be all u need esp if wide enough for a quad/compact tractor to extract timber.
U'll need a ride anyway if u intend on putting a real deer fence up in future
Mibee different down south but i know alot of my boundries which are foresrty just says "undefined boundry" so i don't really know exactly where most of my boundries are. And it was bought direct of the main landowner so not divided up by 3rd parties