Welcome, Hermann - nice 'problem' you have there... (I have a1200gs, 1200 adventure, 1250)...
The newish KOVE bike, from Offroad Motorcycles (Koedoespoort, North of Pretoria) ticks a lot of 'long-range Plastic' boxes, being 450cc, with a 30L tank, and getting very good reviews indeed.
@Runner...