Not sure about your bike, but with my Trance, I can make it fit by securing it on the bottom of the downtube on one side and the top tube on the other. Looks a little weird, but worked better for me than any of the adapters. Play around with it a little bit, you might be able to make it work with no additional items
"Duct tape is like the force. It has a light side, a dark side, and it holds the universe together..."
-- Carl Zwanzig