Make gradual changes to the binding angles.
Try going from 18/-15 to 18/-6 for a day ,then 21/-3 for a bit .then more forward as you feel comfortable.
I made a change in the opposite direction... slowly went from 21/+6 to about 15/-3 . this made learning switch easier for me. The farthest forward I go now with my back foot is 0.
I've seen pros land jumps switch with a forward stance, so it can be done....YMMV
usually more like 10th chair.....