Interesting, I would wear it, I don't think we have that tradition here in NZ and lots of people wear white to a wedding in non bridal ways.
I had a similar situation, i had a one month old baby and I opted for a wrap top and skirt, in a dusky pink. It was a two piece dress really. I don't think it was my best look but it worked, and whilst I never wore it together again I did wear both separates quite a bit, especially the skirt.
How about a jumpsuit, some of them have button up tops?