Why don’t you do the vintage birdcage cake..but put the nautical theme on the cake board? You could place fishnet on the board and add anchors and small life rings?? Know you could probably pipe a fishnet, but a white hairnet would work too. Laid over some fondant rocks. Perhaps a starfish on the fishnet too.
These are just some if the ideas that popped into my head. Hope this helps.
Creativity is God's gift to us. Using our creativity is our gift back to God. Clarky's Cakes 😎