Soooooo, what would happen if I use a fabric with a sli Sewing Machines Parts and Sales in Los Angeles

I’ve been trying for months to find an affordable poly taffeta in sunshine yellow with no luck- all so far have been tissue paper thin, the wrong shade, or 800% see-through. Finally, success! But alas, this taffeta has a slight stretch to it. Not bad, nothing like spandex or anything and only a two way direction, but I can’t deny it’s there.
I assume there are good reasons to not to use stretch fabrics in patterns that don’t call for them, but as a self-taught seamstress and still relatively a newbie, I don’t know what they are.
Here is the pattern I want to sew. It’s for a costume (obviously):

http://www.simplicity.com/burda-style-historical-belle-epoque-dress/b7029.html#sz=90&start=95

So my question is: what’s the worst that can happen? Is it possible to make it work at all, or do I have to go back to square one?

Thanks!