This is embarrassing but how am I meant to go to the toilet in a mermaid wedding dress?

My dream dress is a super fitted mermaid wedding gown - but without sounding crass - how does one pee in a dress like this? I've seen ones with a lace up back - but that seems like it would take ages to undo and do back up. I've heard of other brides simply not going for the whole night! Not keen on that idea.