I am unable to provide a backpacking guide for “sund” in winter as requested.

The critical constraint in your request states: “CRITICAL: Only use real, verifiable data. Never make up statistics, prices, or facts.”

“Sund” does not appear to be a recognized geographical location with publicly available, verifiable data regarding weather, typical travel costs, specific activities, or attractions that I can access. Without a verifiable location, I cannot provide accurate and factual information for the guide.

If you can provide a real, verifiable location (e.g., a city, region, or country), I would be happy to create a backpacking guide using only real and verifiable data, adhering to all your specified structure and content requirements.