It is well-known that attempting to re-enable sailing experience gained from just sailing will not improve anything.
So instead of just turning it back on, it's perhaps better to consider other options that would be harder to script. This is by involving more player interaction instead.
Spitballing ideas, I've come to a conclusion;
Sailing obviously stinks. It's tedious. A challenge, and requires a behemoth amount of XP. But what if we can just reward players for being a Sailor. An honest-to-Makers sailor.
I suggest a new buildable in settlements that are adjacent to an ocean biome.
The following criteria should be respected:
That harbor can only go to other harbors accessible by the ocean-route. Rivers are excluded for this. This means that all harbors can only be found on settlements that are adjacent to an ocean-biome only.
Transportation between harbors must extend to at least more than 5 map-grids to qualify as a "task".
Finally, the person must be willing to compensate the Sailor to ferry their stuff to another valid harbor.
Here's the picture, and then I'll explain more about it.