Buy a packet of one gallon Ziploc plastic bags. Find some padding such as one inch polyether foam, upholstery wadding, rags or other soft stuff, and cut squares that loosely fill the bags. Use them to pad and wedge plates, bowls, mugs and glasses, tins, jars and bottles - all the things that shake, rattle and roll on a rough passage.
It's the Ziploc bag that makes the difference. Padding material on its own quickly gets damp, salty and mildewed.