135 x 135 Holy Cow! That is a large quilt to tackle. I would do something that I would feel comfortable with. The stress of not having it turn out the way I envision would be very stressful for me. All the time spent on such a wonderful quilt deserves the best you can do. There's been good advice here. I agree with others that suggest FM in the darker areas or a more simple design that you are more sure of yourself. Maybe feathers in the dark areas instead of the light. However, "practicing" on a quilt brings on the rewards. It forces you to quilt better than you believe you can. And I have found it really looks pretty darn good when you step back a bit. Whatever you decide good luck to you. What a fun challenge you have ahead. Think how good you'll be after all that "practice". It will be beautiful I'm sure!