Out of curiosity, it sounds like a huge chunk of his property line (at least 1.5 miles) has you as a neighbor. If you build up a rapport with him and he feels comfortable that you will control access from your property onto his, that could save him a huge amount of $$ by not having to fence his property where it's contiguous with yours. It also allows both of you to still draw a wider gene pool for the deer running on both of your properties.
Another question. Does your neighbor live on his property? Are you going to live on yours? If one of you lives on your respective properties, that person could grant the other permission to enforce no trespassing signs, call local LE, etc. If his main issue is trespassers and poachers, there may be a way to come to a more productive agreement that resolves that problem and benefits both of you.