Jeff, if you are gonna wire a rail on, another suggestion or option is to grab a handful of small ratcheting straps and ratchet strap the rail on. You can get it nice and tight and it will flex nice with the wind without fatiguing the metal and breaking like sometimes happens with nails or wire.
One thing we figured out over the years building these types of stands on our own property is that screws and hard nails like the hardened ring shank pole barn spikes aren�t the best because they cant flex or bend very much at all, they snap. And you might not realize it right away because of course they break between your board and the tree.
Heavy pole barn nails that are the smooth shank or just heavy framing nails work well because they can bend a lot and not break.
