I've been smelting wheel weights for about a year now. I'm storing the ingots in plastic stacking crates. I can put two crates on a four wheeled dolly and still manage to roll it around in the garage. Each crate holds about 800 lbs of ingots. The plastic crates are not bearing the weight of the lead. They're just keeping the ingots stacked. You'll notice that the bar ingots on the right stack much better than the muffin ingots on the left.
Here's a picture of my first ton:
How does everyone else store their ingots?