For those that use polystyrene hives (ours are Bee Box/Paradise) how do you over winter? I’ve read some posts suggesting leaving the bottom screen wide open for ventilation. If the hives are on the ground the open venting may be fine but on a open stand, off the ground it seems like too much exposure. Any other suggestion or tips for winter prep? We are in the US, zone 5b and the yard is open with little wind breaks.