That's a good setup, the ground will help you. You can go 2 directions. If you want to stick with the heated deicers you'll need to convert from DC produced by the solar panels to AC, which means you'll have to buy an inverter. If you go with a pond pump or bubbler you can stay with 12v from the batteries and can save the cost of the inverter. I've never seen a 12v deicer, I know they make 12v water heaters for houses but I've never seen anything waterproof.
You could try the progressive approach, get a single panel, a battery management system and a few batteries and see if a bubbler can keep it thawed. If not you can add a panel and a few more batteries until you find the right solution. Are you able to throw a piece of insulation over the tote at night? That would really help reduce the power requirement to daylight hours. Since you're a farm you probably don't need any inspections, you could ground mount the panel on railroad ties to keep the cost down.
I assume you have a backup plan if the solar isn't enough. I have a PTO generator for my tractor, if you have something like that you could park the tractor out in the field for the really cold spells when the solar can't handle it alone.