I'n not familiar with the rig of a Y-flyer but if it has spreaders and a backstay I'd be tempted to just raise it and tune it plumb with the standing rigging. You'll probably have to keep at it frequently but eventually it ought to work back to shape.
I can just see trying to bend it and suddenly finding out that last tug or push was too much. From what I've seen when they go they do it all to once. (Had a wood one let loose on me and it sounded like a .30-06 blast!).
Charlie P. P31-2 #80 CATNAP
To travel hopefully is a better thing than to arrive - R.L. Stevenson
I suspect that, if you should go to the end of the world, you would find somebody there going farther . . . - H.D. Thoreau