Heinz,
A Mercedes "Magic Wand" does everything, indicators as normal, then lights as you describe and finally wipers and screen washers by turning and pushing the end of the wand. Although complicated they seem to work and last. I wonder if one could be adapted to fit!
Back in the "good old days" the wand, on RHD cars, was on the right, so that the left hand was free to change gear. On LHD cars it was the other way round. We have the EU to thank for forcing the "indicate on the right" rule.
So, for all RHD Morgans a Mercedes wand on the right side would be just about perfect!!
