Storing potatoes in hay & plastic?

About to harvest my potatoes.... I have extremely limited indoor/covered space, rodent issues and a humid, very mild (no snow at all, but pretty wet).  I can get $5 thick 200L food grade plastic drums practically new, with air tight snap lids, for $5, & I have a load of hay from our property.  SO, I was thinking of storing the potatoes in drums, layered in hay (I only grew 4-5m of them).  
Looking at how others have stored potatoes, they say they need ventilation, but they have also been stored in clamps in the ground, so surely they don't need heaps of ventilation then.  
How many holes do you think I'd need to drill in the drums to give enough ventilation?  I'm going to store the drums outside so thought perhaps behind a building and holes only drilled on one side  to protect from driving rain.  And/or maybe I'll put something over the top of the drums as well if I can find something.

We store potatoes in bulk in cardboard boxes, without adding filler.

Potatoes don't store well in high humidity conditions, (thus the suggestion for ventilation), so I would hesitate to store them in plastic, unless the container didn't have a lid...

I use cardboard boxes, with layers of newspaper between layers of potatoes. Personally, would not put them in plastic. Too easy to cause rot.

Why not get a metal trash can instead?

Small holes could be drilled ever so often for ventilation.

I have seen evidence that rats and mice will try to gnaw into plastic.

A metal bin would be at least $41 more than the plastic tubs I've got access to....and would be a quarter of the size.  
The plastic drums are very thick and while I have no doubt with enough time to work at it that rats Could chew through them, it would take them a long time and if stored outdoors I don't think they would bother.
I preferably need to store the potatoes outside to save on indoor space as I said.  I know there wouldn't be much ventilation in a plastic drum, but if storing potatoes in clamps in the ground is a done thing, is a drum with holes drilled in it any different?  Apparently 90% humidity is good for storing potatoes, did I hear incorrect??   I am drying them out indoors first...