In these applications, if you are willing to spend the money and you don't want to mess about with wireless LANs, I would recommend buying Ethernet/Optical converters on each end and running cheap multi-mode fiber between the buildings. Lightning cannot transit optical fiber, and with that impressive inventory of smoked, the cost of the converters on each end gets to look pretty cheap.

The one hurdle in installing fiber is the connectors on the end. Everything else is pretty easy, but the connectors are a challenge compared to wire. If you want to check out fiber, you could buy a run of fiber with connectors already installed (the easy way to go), or read up on connectors in the following URL:

http://www.fiber-optics.info/articles/connector-care.htm