Wow Darryl, that DOES sound like a FUN adventure!
I wish you lots of luck for a trouble free ride, and I also expect that your BMW will trounce many inferior bikes along the way! The preparation on this is going to be critical, I think. Have you already been through your R52 crank, journals, etc? Does the R52 use the same type of slingers and general oiling system as on the much later /2?
I think that a BMW stands a good chance on these types of 'endurance' races - bikes like a 1929 Henderson would likely take you as far as top speed and HP goes, but I can't think that those inline-4 aircooled engines would like that kind of continuous operation..