In terms of treating the cabin wood, the cladding doesn't strictly need to be treated as it's been through an intensive heat treatment which stops it from moving with weathering but sunlight will weather it's appearance a little and make it look greyer. If you want to keep the color in the wood then you can treat it with an oil based substance.
Here's a paragraph from the wood manufacturers guide:
5. Surface treatment To prevent colour changes and other natural effects of weathering it is recommended that surface treatment is used. Oil-based substances work well and in a similar way as with untreated wood. When working with water-solvent substances it has to be taken into account that ThermoWood has a lower water absorption rate than normal wood, this can have an effect on drying time and penetration. Results are also dependent on the paint application and drying process. The paint manufacturer’s instructions should be followed.
In conclusion adding of a layer of creosote on the outside doesn't hurt.