When camping in a tent along the way: 1. do you use a ground sheet and 2. do you put it inside or under the tent? Many years ago I always put it under the tent to protect the floor from sharp objects, and thought it protected the interior from rain water; then I read an article saying that it should go inside as placing it under the tent will work to trap water between it and the tent floor, increasing the probability that water will get into the tent. Anyone have thoughts or preferences?