Let me introduce you to a concept of lonelyeyes wedding at the sea.
First of all Elias would for whatever reason agree to leave wedding plans on Peter. He would possibly really need to marry him at the moment and Peter would give him condition that he has to let him plan it. Elias expects something very tasteless but he agrees.
So Peter plans wedding at sea since ship captain can officiate a wedding in international waters. He even knows at least one captain - I mean Mikaele Salesa might have some lost bets and owns Peter a favor so he can ask him to perform the ceremony. He also force the whole crew of Tundra to attend.
Overall Peter is having great time for once. As the only one. Because Elias is probably suffering from seasickness and he's also nervous from being on Sea, Salesa would be uncomfortable as well as the crewmates.