Well, a Dokker doesn't have a lot of space, so if it were me I'd go with making a sleepable flat surface, curtains for privacy, and call it a day. Use it a couple of times and then work out what you really need to take with you because everyone's needs vary!
One tip is to pitch a tent or have a roof rack to put all your stuff in/on while you're sleeping in the warm/ dry /cosy van.