The big thing, in my opinion, to watch out for in staking out are rope burns from the rope wrapping around the legs and what happens if the horse panics when the rope catches him. If you're using a cotton rope that will help lessen a burn if an incident does occur. If your horse has been staked out before, hopefully he's seasoned enough to not panic (you mentioned 'several years ago' so he may be rusty at it so take extra care).
I have heard of people tieing by the halter. I have also heard of tieing by the hind leg. Perhaps some of the forum members who have packed into the mountains could comment on this technique if they used it on any of their excursions.
Just for the record, I personally wouldn't tie any of my horses because of their temperments and training. Otherwise, watch him carefully and good luck.