No,
@Broch , you are wrong!
An experienced person can live comfortably in such a thing.
My construction trailer is 340 x 220 and 195 to 240 cm high. It's fitted out with a cheap work shop oven in the corner next to the door, a open (!) wardrobe case in the other corner at the door, diagonal from the oven the sofa / bed box 200x65 and 45 cm high, self inflating Therm-a-Rest on it, because it can't get damp if I don't use the trailer, from the pillow I can see what's going on with the stove and have the maximal possible distance to it.
In the other short wall, opposite to the door, is a window that I rarely close totally, under it a 120x40 table, 77 high that serves as writing desk, eating and night table.
All around the walls hooks to hang stuff and dry clothing. Additional washing line in the highest point of the roof for socks. Washing line over the bed to air the sleeping bag. Like this I can dry a full load of a usual washing machine, or if I got whet outside.
I insulated a bit the walls and did put wooden boards inside because I have a metal trailer. But I even didn't insulate the roof, because I was afraid about condensation problems. The metal walls are open to outside at the lower end that water can drop down and the space there can dry.
Behind the oven I attached steel plates with 5 cm air space to the wooden wall in order to protect it, that it doesn't catch fire.
I have one wooden chair that serves as additional drying stand too and a box for firewood.
Relatively near to the stove hangs a hook from the ceiling to dry the boots or really whet trousers. I just put the laces together and hang the boots nose high. Next morning they are dry.
As you see, I build a drying room to live in. And that's why it doesn't get damp in any way. I make my clothing bone dry before I lock it into drybags in my bed box. The shepherd's surely had less clothing and like this the storing problem didn't exist.
In such a trailer the secret is really:
Less is more!
The less stuff you have, the easier you live in such a thing. I am currently sorting out not needed clothing and other stuff and get rid of it. One can of course have a bit more than a 120 litres winter trekking equipment, but let's say 300 litres belongings are surely the maximum that's sensible here. I guess 240 litres trekking equipment is ideal. I will try that out now.
My only problem is, that my cheap stove is constructed to heat a larger room.
It doesn't become too cold and damp here during the winter, my problem is, that it sometimes becomes too hot if I did put too much wood into the oven.
My set up is made for - 25*C, the lowest temperature that I have to count in around Berlin. Around the freezing point I easily overheat it if I don't pay attention and than can't close the door if I want to sleep.
The most comfortable it's here if I don't need to heat over night or between -5°C and -10°C.
But that's of course a question of experience with this oven, and in the old times they offered better fitting smaller ovens.
I fitted out the construction trailer pretty fast, as I got stuck here due to the pandemia. I didn't search for smaller ovens in the internet and just bought what was offered in the next hardware shop. I guess one can find smaller ovens too.
My garden house in Berlin is 4 x 3 metres and the ceiling is higher. It's fitted out pretty similar.
My construction trailer is more comfortable than the garden house, although the garden house has a very expensive strong oven.
The smaller thing is easier to heat up if I come home. You wait less long until it becomes comfortable.
I did showel the snow from the ways in half the garden colony by hand, every evening 50 metres, mainly because I didn't want to sit in the room and wait until it becomes warm. Such problems I don't have in the construction trailer.
It heats up immediately.
