Root cellar design - one or two intakes?

We found a 8x4x3' pre-cast tank on our property and are using it to make a mini root cellar. Our understanding is that for small cellars, best practice is to have a low intake at one end and a high exhaust at the other - to pull the air/gasses through.

The tank has low holes on both sides, and therefore could potentially have two fresh air intakes - with a high centred exhaust.

In theory, two intakes would circulate more air, but might risk dropping the interior temperature too low - especially during cold snaps (we can get down to -25C). Looking to the permies community for any thoughts on which approach may be better! TIA!

No idea, but cool find! And hopefully someone else will have experience to help.