You and your son need radios so if he or you need to skedaddle into the brush for a few hours you can find each other. Using your white out example if he was forced out of the house he would need to communicate with you. In a whiteout if someone is trying to steal my horses I think I would just start shooting and ask questions later. In a SHTF you need a bug out plan that includes leaving in all weather extremes, all. You need a fall back location with shelter in your environment. Maybe build a shed that will be a snow cave in the winter. After it snows make several paths leading to different locations so it would be difficult to determine which path you took to escape. You don’t want someone to just follow your tracks right to the door. Have a way to jump the track so it’s not obvious where you went. Sking over hard ice doesn’t leave tracks for example. Wet the snow with a sprayer creating a think crust where you plan to get off the trail. I’m sure you can think of other methods these just come to mind.