So, here’s the update:
For 2000ks after the original post I did all the wiring and carb checks (thanks for the suggestions, Oakes!), but the problem persisted, very randomly.
Then , timeously (with a big trip coming up), LeCap weighed in with his assertion that it was the side-stand. Thank you, Jurgen! I disassembled the unit (in the up position it was rubbing against the swing arm) bent the shaft accordingly, re-tensioned the springs , lubricated everything , including the switch, and voila! Just did a 3000k trip with no problem. Rode with Ri, who owns several DR650’s, none of which have a side-stand switch - for all the obvious reasons.
Oh, and just for the record, my bike has 25k on the clock, and on this 3000k trip (Northen Cape/Boesmanland...2500ks on dirt), not a drop of oil used, no chain adjustment needed, best consumption 26km/l and average consumption overall 23km/l. That’s carrying quite a load (self-supported for 10 days with full winter rig and camping gear). Look out for Ri’s RR soon...