I received a large box from Vivid on Tuesday. The styro box was taped around, it had 6 or 7 heat packs in there and they were still warm to touch. Also the box was full of peanuts. The shipment basically traveled through the whole country... from CA to NC... was shipped around 6pm ET and arrived to me 1pm ET next day, so under 24 hours of travel time.
I'm expecting 3 shipments next week and will take better notes.
I think the larger boxes definitely help with enough oxygen, but you need a bunch more heatpacks to control temp. Shipping is crazy high for the average guy on a large box like this, but the vendors get deals for their volume.