According to Lumley, this is what Neanderthals did in Grotte du Lazaret, in Mont-Boron very near to Nice.
Inside the cave, make a hut, 3.5 by 11 meters (11 ft 6 in by 36 ft 1 in), using one cave wall and surrounding the space on other three sides with skins. And with a roof of skins as well.
Inside the hut, make beds by dried seaweed covered with skins and make two fireplaces, one near each end of the hut.
Use the fireplaces as dustbins too.
Should be enough for a Duggar sized family, or for a few smaller ones./HGL