How about two feet down in the end zone? In the field of play it has been interpreted as two feet down prior to contact. This was from a play in 2008, the
video (see Collinsworth commentary @ about 3:35) of which I have previously linked to. If all you need to do is have two feet down in the field of play, prior to contact, to avoid the stipulations set forth in the "going to the ground" rule, it seems to follow that you would only need two feet down in the end zone if you fall from your own momentum. Especially given the clear language of 8.1.3 item 3: End Zone Catches.
I was hoping more people would look at the link and chime in, but it seems we are all so locked into our own view of things we are not budging. One side certainly seems to be asking the pertinent questions, however.