For all those that come here looking for an answer that is buy v build:

https://www.superknuckle.com/product/Pannier_Adapter_Rad_Power/23?cp=true&sa=false&sbp=false&q=false&category_id=9

A company called SuperKnuckle actually makes an adapter.  Just ordered it.  I haven't tried it yet, but the $16 price tag is where my DIY parts list was coming at or above, so I thought I would toss the dice.