I've heard Cotton Patch geese are usually even tempered and calm, too. Does anyone here have any? I know there's a farm that has a lot of them (Flip Flop Ranch maybe??), but I don't hear much about them.
DG pilgrims are known to be calm also. But the geese will need seperate housing from the chickens no matter what the breed. The pilgrims however are a smooth feathered bird so can be housed more like your LF ducks with winter protections.
I don't know any Sebbie owners who live where it snows that dont have a fully enclosed shelter or barn for the,m to get into. They do go out during the day in winter up north, but always have shelter too.
Never jump into a new species or,breed without doing research on the basics. Food, water, shelter after that it's about your property and if you can accommodate the needs and keep them contained and safe.