Bring a survival kit for your poor Bride. Tampons (not only for the usual purpose, but for sopping up spills and things they are amazing.)

... ew.

I didn't elope, but I also didn't presume to dress anyone other than myself or demand that someone else pat my hand and keep me from hysterics. She's not being forced to marry, after all.

I'm not even sure why someone would want to want to have a wedding like this. Even if everything goes right, the result is so... generic.