I found some stores are using plastic, stack-able pallets to move products around. These seem designed to carry a lot of weight. The downside is, they are designed to stack tightly, not with air gaps between them, so I'm not sure how much strength they'd have if they were stacked irregularly in a way that provided gaps for lots of water. I also couldn't find a local source to purchase these, as the local stores seem to reuse them. And on-line they can be as cheap as perhaps $20, but shipping fees are very high.