Where to find a property up North for Sunbirds / reverse snowbirds?

I'm a bit confused what you are asking for. Assuming it's setting up a campsite on private property, the biggest challenge is likely to be zoning. After that, basic utilities (water/power/sewer). 

Many places won't let you do it at all and others have a lot of permitting.

Assuming you have googled “alternatives to AirBNB” and you are rejecting that whole business model, for whatever reason, then your choices are rather limited. I suspect this is something you already know. I think you’re stuck with posting ads in publications with wide circulation in the target areas.

• Pacific Northwest:
  • Washington State: Areas like the San Juan Islands, Bellingham, or Olympia offer cooler summers and stunning scenery.
  • Oregon: Consider the Willamette Valley, Bend, or Ashland for mild weather and outdoor activities.
• Northeast:
  • Maine: Coastal towns like Bar Harbor or inland areas near lakes and forests.
  • New Hampshire: The White Mountains region or Lake Winnipesaukee.
  • Vermont: Small towns like Stowe or Burlington, known for their charm and outdoor recreation.
• Great Lakes Region:
  • Michigan: Traverse City, Petoskey, or the Upper Peninsula for lakefront properties.
  • Minnesota: The North Shore of Lake Superior or the Brainerd Lakes area.
  • Wisconsin: Door County or the Northwoods.
• Rocky Mountains:
  • Colorado: Towns like Durango, Steamboat Springs, or Estes Park.
  • Montana: Bozeman, Whitefish, or Missoula.
  • Idaho: Coeur d'Alene or McCall.
• Canada:
  • British Columbia: Vancouver Island or the Okanagan Valley.
  • Ontario: Muskoka Lakes or Prince Edward County.
  • Nova Scotia: Coastal towns like Lunenburg or Annapolis Valley.