It all worked very well but will be changing few things through the winter.
Will be adding a vent at the bottom of the door - as it is, the trailer is sealed too well and when in outdoor storage, there is no place for colder air to come in so, with just the roof vents open, it's like a baking oven.
Planning to make a hatch to access under bed storage from outside.
Possibly
paint the outside (off) white. The colour we have is a bit too dark.