Glad you have a solution that works, at least from the inside.
I see daylight in places around my 1981 vintage wooden pilothouse doors, warped too much to get near door seals in places! Spray has not been much of a problem to date. There is about 0.3m overhang of the pilothouse roof above the door, so rain is generally not an issue either.
One solution, for closing either inside or out, would be to install an 'espagnolette' bolt kit. These things are often used for French doors.
Some security screen doors use them also., with internal mechanism.
I don't have a source for marine-type ones....