Dd is going on a 3 night D of E expedition in a couple of weeks and I'm sorting out clothes for her. On the website they recommend a short sleeved t shirt in a wicking fabric with a fleece and waterproof on top as layers. Would it be better for warmth at night and sunburn avoidance to get long sleeved? On the other hand short sleeved would be cooler while walking as it's set to get warm where we are down south