Ships became an important part in AC4, so who ever makes the trainer will definitely take a look on it without giving a promise.
I think you both should, or atleast consult eachother on the making of it and maybe combine a little, like with dishonored making them "compatable" because you both make some good options but each trainer is always missing one option that can be useful, This is not a bad thing I don't try to talk bad about the trainers just stating how it felt about AC3 trainers, each one had an option missing that was on the other trainer.