Lay on the engine
Use padding to protect you, and lay on the engine.The other method is to remove the inboard panel of the quarter berth. (This is the one I used.) But the screws holding the panel to the bench/berth are even harder to reach than the stufing box, so you need other reasons to take this approach. (I was mounting soundproofing around the engine compartment.)DavidLady Lillie