Much depends on how well you can level things out inside of the soft bag carrier. Smoother surface on the top of the bag means less wind resistance, lower fuel cost and less potential stress on the zippers and seams on the bag. So maybe bin boxes will work or maybe individual bags will be better. You just have to do some test with how things fit and pack. Sometimes items may need the physical protection of a hard sided bin. No one but you will know what is going to work best because they are not the person packing up for the trip.