The plan is for a cheap and lightweight trailer.
It will be 8' (2440mm)by 4' (1220mm) based on the size of a sheet of plywood and also I don't have a workshop but have enough room in my basement flat to build it that size in sections then can put it together at a later date. Not sure about insulation yet whether to go for 25mm or 50mm as it will be used in colder weather.
The sleeping area will have a futon in it so it can be used for seating as well as sleeping and the rear will contain the kitchen area where I will be using my old camping trailer fridge (12v,240v and gas) and my camping gas hob, I will have a 12v battery hopefully I can find a cheap zig unit so it can be charged whilst driving and run an invertor and have 240v just to run the fridge but that isn't essential, the lighting will probably be battery leds just for simplicity.
Here is my first basic plan

Its turned out quite boxy but that is because of its small size and what i want to fit in it. Any help and advice gratefully accepted.