LJ,
My sources are many, and nearly as many of them hail from Nebraska as from Lincs and Lancs.
I don't think anyone uses the term 'flatbed' to imply ro-ro - just an empty shell which would be cut and modded to allow kit to be installed - just as one of the existing R1s started life as a 'flatbed' MR2.
Rolling it on, perhaps, but not rolling it off.
I like your pics, which are very good illustrations of your point.
You will have PM. But not before the morrow.