I have a couple 300 gal Rubbermaid livestock tanks that are 2-feet deep. Just not sure if it is a good idea to overwinter a water lily in them. Maybe too cold and might crack with ice? I have a lot of projects planned, so I will probably continue to hold off and wait for the price to come down, and/or for better hybrids to be developed.
Update:
"Rustproof, Dent, Crack & Corrosion-Resistant Even When Frozen Solid"
https://www.ruralking.com/rubbermaid-farm-tough-300-gallon-stock-tank-fg424700.html