I just finished putting 2 center tie out points on mine over my lunch break. Now mine can be pitched in Winter mode with doors just like in gmcttr's picture.
Let me tell you, this thing is Bad A$$ when pitched in winter mode.
For sewing the tie out loops I used the directions for Test #5 from this post:
That is not the way I have sewn loops on all of the tarps I've made, but it is hard to argue with NomadicPsyche's destruction test results. This is very clearly the strongest method that he tested.