My dog enjoys hiking. I haven't taken her on any overnight trips yet, but would like to try some summer/fall backcountry camping with her (i.e., what I think Europeans call wild camping -- not car camping). The wilderness areas near our home (Los Angeles) are mountainous, so it will be cold at night, even in the summer. I'd like her and me to get a pleasant night's sleep. I usually don't bring a tent (do sometimes bring a tarp) for summer/fall backpacking in California. She has fur, so I'm sure she could survive the overnight conditions just sleeping out in the open, but she'd probably be unhappy, and would whine and want to crawl into my sleeping bag, which would be uncomfortable for me.
Does anyone have any experience with this and suggestions for how to do it? I would prefer something compatible with an ultralight style. She's small (10 kg), so I could let her sleep under my lightweight down sweater, but she'd probably damage it. I wonder if it would make sense to get a cheap, used synthetic sleeping bag and cut a piece out of it for her to use as a blanket?