Neighbor Issues Property

[James Edwards]

Anyone ever dealt with a neighbor/property line dispute? Purchased some property from an elderly couple, who never got around to developing it. They were also tired of dealing with the neighbor. 

Own a flat surveyed vacant lot, behind my lot is a small strip of land appx 12' long by 100', the edge of this section is a pretty steep embankment.

Neighbor A owns it, and lets Neighbor B park on the small strip. 

Neighbor B has been using my lot to access it, as my lot is bare/ vacant. Neighbor B has left garbage/junk on various sections of it. 

Recently I have sent a letter to Neighbor B, nicely telling them I am going to be developing the lot and installing a fence. They need to remove their "items" from my property, and refrain from using it to access this "strip." I told him the fence is going up in 14 days. 

I have been wondering, what exact options do I have should the Neighbor decide to not remove his stuff, or B. hassle me when I am installing the fence. 

Thanks!