What is the purpose of the fence, just to mark the lot line? I have just shy of 80 acres with some challenging topography (including a 50 foot deep, 100+ wide ravine that bisects the SE corner) so other than posting, I have no interest in going to the expense and trouble of fencing the lot line. I know within a few feet where my line is after consulting aerial & Satellite photos, overlaying topographic maps on plat maps in Photoshop, traversing the line and finding marks, including some old slashes on border trees and well marked paint marks where it borders on the South side with some NY State land and of course the corner posts (capped galvanized pipes in my case from a 1960's survey). So this has allowed me to be fairly accurate in posting the line which is on three sides all heavily forested. The Western line which has a number of oddly sized lots (each 2 acre or so) is more problematic, so I have been more conservative on posted sign placement so as to not inadvertently place on someone's back line. We are in the process of clearing some acres for agricultural purposes and I plan on a good deer fence for that area, but there will be a wide forested buffer between the cleared areas and the property line.
But to go to the considerable expense of a border fence on a large forested lot (survey costs, fence materials & time) without other mitigating circumstances (such as a neighbor improving his land up to the line) I don't see the benefit.