I just went through this last night,and I was afraid to cut the fabric so I left it all on until I sewed it boy I'm glad I did
because when I turned it over to look at it,my stripes were way off,I didn't think about it,so I thought there has to be an easier way to this so I did what you did so I could see what I as doing eccept I didn't think to iron it first YOU are right this is the best way at least to me,I did a good job considering it was my first attempt
Wendy