Too add a bit of observation about our communication.
When English speakers read the translation of this phrase as 'The sheets are justified', we run into an interpretation problem. To a native English speaker, the word 'justified' in this context sounds like a moral or ethical defense. Because of this, many people think the sheets were hung for reasons of modesty (for example, to screen off the girls), and that the diary author is defending that necessity. We don't immediately realize that it is purely about practical utility and retaining heat.
Having read a bit more myself about other hikes and trips. The tone of the diary as are others is nothing but humour and story telling. I now feel I have better understanding and context of this section of the diary .
What I do believe is when the stove is working or in use , the heat is extreme in these tents. In other hikes they talk of lying barefoot, in shirts and on top of sleeping bags when the stove is in action. I can testify to this from personal experience that a stove in a small canvas tent can get extremely hot.
Sewing a baffle or drape to the front area of the tent is standard practice and it also came in the form of a tunnel chamber .
The context of the excerpt makes sense when we read the previous sentence in the sequence.
The stove is great. The two engineers in the group are joking with exaggeration about making central heating for the tent , it's the same humour used in the combat leaflet and every other winter hike report.
The talk of the drape or curtain just means it was worth all the trouble and it's now paid for the hassle of sewing it and carrying it. It's a team spirited compliment within group.
Every hiking report speaks of the useless sledges that they took and don't work( one group burned the thing in the stove), skiers going ahead to make paths, tents with holes in them , stoves with problems, getting lost, getting up late , blizzards . Every hike had the same equipment issues , humour and difficulties and at least four hikes reports , hikers dug dug snow caves to shelter and one group through 1.8 meters of snow to get water.
I would think , the curtain is just a draper for heat , the stove is what divides the tent and our English translation missed the nuance of the context .