I believe it will be unstable. I changed the shock on a few Telelever bikes, but never gave a thought what happens when I am not supervising... As I recall, I had to support the machines the same way as when removing front wheel.
However: how about a bike cover? Even a tarpaulin, if dedicated covers are expen$ive in Korea? If they let you cover a bike in your location, this may be the best choice, the bike looks uninviting.
Happy New Year!