big wall anchor building

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I can't really answer your question, but I have wondered the same thing. However, if you click your link, looks like that is a 4 bolt anchor, is it not?

Typically on modern wall routes there is ample space to get separation for all the gear. At likely portaledge bivies usually there are 5 or 6 bolts spread out. Two bolts is pretty unlikely.

I like to set up a master powerpoint as the main focal point of the anchor and then have a secondary haul point off to the side. Depending which way the next pitch leans, left or right will determine where I set up the bag. This keeps things really clean and makes lowering out a breeze.

I like to carry to dedicated slings for creating the main anchor powerpoint and the hauling point. Complete with biners, etc.

I'm sure by the time Chris Mac completes his "how to climb bigwalls book" I'm sure there will be ample diagrams and photos of good BW anchors.

Like John said. The most obvious thing to do is when you get to the belay create a bomber anchor for yourself, and your second. Then create a bomb anchor to haul off of. This way if you do set up a bivy you already have a good anchor for your ledge, and another good anchor for your bags. clove a line inbetween, and you have space to hang essentials you might need whenever.