Something easy and durable is car tire inner tubes. You can get all different sizes and they can be lashed together to fill the nose pretty easily. Plus they're durable. Make sure there's nothing sharp to poke holes in them like screws holding on the rub rail, or something coming through the bulk head. I think Harbor Freight sells the small ones for trailer tires. Other people use those foam noodles, but they will eventually die and turn to shit, plus they can be kind of pricey if you buy enough to fill the nose. If you can find the ones used by boat manufactures back in the 70's-80's they were like air filled pillows about 16" square, made out of a pretty thick vinyl. Those work great IMO, but don't know where to get them.