I have Vizslas. Thin coated dogs that feel the cold. I’ve had a couple of nights when they’ve felt the cold even with efforts to prepare. I have a couple of fleece coats that I carry (1 at a time) along with a cheap mock sheepskin mat I bought from Lidl or Aldi (one of them has dog stuff for sale at the moment). As a final resort, when it’s really cold, I carry a back up down Alpkit blanket/quilt thing which I will sacrifice to help keep my mutt warm. I’ve had to sub zero nights in the past year.
I am currently planning on experimenting with a Decathlon children’s fleece top which is better quality than any of the dog fleeces I have tried but needs some alteration to get round the dog leaving the tent for a pee and returning wet.
Like their human, my dogs appear happier with layering. However, space/weight are at a premium and, although they can carry their own food for a few days in bags across their back, I need to carry their rain jacket, pyjamas and anything else to keep them comfortable