As I've already explained, propane is not the answer, for me.
It would be impractical to source or store enough for an extended stay. A few nights maybe. Never mind having enough space in the gas locker for it. Continental autogas is no good, it's normally a propane butane blend, in winter the butane just lies uselessly in the cylinder, with every refill you have less and less capacity. As I have discovered myself.
Not a problem for automotive use, they first boil it up in a heat exchanger using engine coolant. UK autogas is nearly all propane, much better.
LPG chills as it vaporises, the bottle becomes far colder than the external temperature. Even in summer if you have a heavy demand a propane bottle will go sub zero and frost form on the outside at the liquid level. It would have been game over long before then with butane.
It would not be usable anywhere remotely near -44 C, that's simply when the liquid's vapour pressure equals atmospheric. The colder it gets the more energy it takes to vaporise it. See
https://www.engineeringtoolbox.com/latent-heat-vaporization-propane-d_1203.html for data.
In a gas cylinder that energy comes from the surrounding air. Which is static when enclosed in a locker. Or you have to fit a heater to it, e.g.
https://www.amazon.com/propane-tank-blanket/s?k=propane+tank+blanket . Which requires electrical power.
As the cylinder empties the problem becomes worse.
I had some roofing done, and the chap used a huge 47 kg Calor cylinder that he lugged about on a sack barrow. I was surprised, but he explained that even a more manageable 19 kg cylinder could not keep up with his torch when it was chilly and not full, never mind when two of them were working together.
Try to extract say 4 kW continuously from a 13 kg bottle in an enclosed gas locker, and propane can still struggle and become extremely cold as the cylinder empties. The smaller the bottle, the lower the liquid level, the worse the problem. Might work OK when full, not so much when nearing empty.
No, I see diesel as the only practical solution and far safer. Besides, I need an additional heat source anyway, the Truma is under powered, I have a massive 125 l fuel tank that I rarely brim (enough to get me from my house to the south coast of France without refilling), so it is logical.
Not concerned about diesel waxing or gelling. The days of truckers having to light fires under their lorries to warm the lines and tank are behind us. It will be winter grade where I plan to go.
https://en.wikipedia.org/wiki/EN_590