Stretch Fabric and Remove Buttons on Seashore?

Thinking about using this as the starting point for a costume. But I'd like to modify the shoulders to be closed seams and use a stretch fabric. From those of you who have sewn this pattern before, am I crazy to attempt it with a stretch fabric? Any tips or advice? (This was the first Oliver + s pattern I bought, but my daughter is just shy of fitting into a 5, so this will be my first attempt at this pattern.)