As it currently stands, we won’t be able to play coop over the Christmas break, because the beta is only a mere 4 days. Such a shame, and it feels very bad.
This could be fixed, by opening the beta for 2 more weeks.
This is early access after all, right? 
I also thought the 4 days was a bit strange. At least 1 week, so people can contact each other and find a day, not everybody can make that happen in 4 days.
Agree. A friend already purchased the game, played and streamed on discord. More people want to buy it to play during Christmass, but won’t if we cannot. 
The devs may extend the beta. They also gave hints, making it seem like it will happen.