It could be much simpler than all of that. Mary Mapes visited Burkett during the summer according to reports. What if she generated them right after visiting with Burkett (with his tacit approval)? There were some obvious mistakes about TANG in them that you wouldn't think Burkett would make.
That would explain why Rather is so adamant; he doesn't know that Mapes faked them. That also turns things around and makes CBS the source of the memos rather than the DNC.
"There were some obvious mistakes about TANG in them that you wouldn't think Burkett would make."
That's been bothering me as well. Burkett would have known the proper military terms and designations which eluded the forger.
Also, would Burkett have known about the Houston Longmont address? Mapes, remember, has been working on this for five years.