For 23 years, +\-, we lay birds on a piece of raised 4’ x 8’ plywood in a garage…assuming it gets down to 35 or so at night…probably 6000, 7000 birds, likely more, have been through the routine…usually hunt part of Tuesday or Wednesday-Saturday, travel Sunday…never had an issue. I historically do 6-8 trips with 4-8 guys, usually at least 50 birds on the board by Saturday, oftentimes closer to 80, 90, many trips over 100. Not suggesting anybody change their routine, but this works just fine. I wouldn’t do it if it didn’t get sufficiently chilly at night. Important that birds aren’t touching one another. One year some birds went missing, we thought a farmer was messing with us. A cat moved about 8 birds inside the garage, hiding them behind some plywood leaning up against the wall. One bird may have been gnawed on a bit. We stay in a new place sometimes, same owner as the other place, and we use pallets lying on the concrete floor of the unheated shop…better air circulation with pallets, I suppose…