Nice one @barbagris - I somehow knew you'd end up pulling the trigger as you'd been looking and talking about the Mosko-Moto stuff for ages!So - An update.
I decided this morning to order a full set of Mosko-Moto Luggage. I over ordered with one or two accesories that I may or may not actually need - to avoid having to order again later. And their steel-core straps whilst TOTAL OVERKILL upped the price a bit.
I may need to get inventive and make up a rear lashing setup. We'll see after it all gets here.
R80 plus Nomax tank bag - additional pockets - will have about 100Litres of capacity. More than enough.