I did it ... and I did it without harming / molesting / drilling the frame. I'll get you a few pics when I get home ...
Version 2.0 of my 'home build' would have a spring on it ... but I can show youhow that would happen.
'85 R80RT G/Sified
<|> '91 R100GS Bumblebee <|> '73 R75/5 LWB
Airhead Zen: Ride - Repair - Ride - Maintain - Ride - Repeat