Your dog needs to be more assertive, and probably will be with practice. I hiked with a Dalmatian for many years and when it was time to sleep he simply regarded me and the sleeping bag as furniture. Used to circle around and knead me into a comfortable pulp before laying down. We usually found a way to keep warm without anything extra. Sleeping in the open I'd scrape together debris to pad the ground but he'd need some extra help then, a tarp to keep the wind off. A pad of leaf debris under your tent floor might help.

Jimmy T