Make an area with your rope or tarpaulin. Ask the whole group to try to fit inside the small area.
When the group succeeds, decrease the area by shrinking the circle, or folding the tarp and challenge the group again.
Continue shrinking the area until the group are no longer able to fit everyone in the area.
People are going to need to feel physically comfortable in order to get close and be supportive of one another. So make sure people are warmed up and have removed jewellery, watches, etc.