If I had the OP's challenge and I had aluminum welding skills, I'd design a kickstand in the form of an upside down "Y". Vertical leg would run behind the seat tube with padded aluminum semi-hoops similar to those on crutches of long-term users. Just above the chainstays, it splits and short plates run down with a bolt running across serving as pivot for the "V" of a double kickstand with a padded plate across to support the bike's weight. (Don't build this without researching further. I've invested about 1 minute of time above typing time on this concept.)