The idea is as simple as introducing a special way to modify dugouts (or perhaps just a new boat entirely) with special materials to make it 'fancy'. Then, a corpse would be placed in the boat (which should be on a non-river coast, of which leads into ocean water), with the option of sending a few other items alongside the dead corpse (perhaps the items could impact recovery of stats somehow, i.e requiring gold sacrifices to bury a corpse without a skull and still get the 'skull' lp gain).
Afterwards, a person should be able to interact with the boat, sending it off into the horizon and seas, and having it catch fire as it disappears.
Functions as a way to bury bodies without needing a 'graveyard' persay, and for a bit of larpyness.
Another idea was a sort of 'cremation' burial; where you could take a (non-decayed) corpse and place it upon a bonfire, and set the bonfire aflame to have the corpse slowly burn into ashes. Feasting while the fire is lit might even provide a much larger bonus to FEPS as people eat, depending on the total LP/stats of the person being burned. After the fire dies, ashes would be left in the bonfire pit which could be collected in an urn- considering the body as buried. Cremated ashes might have some other hearth-magicy uses in the future too, although this suggestion is just for the burial aspect.
Cremation was a common form of burial in ye olde times, and while real burial by sea wasn't that common (at least, not the 'send the ship into the seas' type), it still fits the fantasy, I think.
Ultimately, I think having various burial types that each provide their own separate inheritance benefits would be cool overall.