"A half-mile or mile is plenty, and still close enough to civilization should anything go seriously wrong."

I'm not sure I agree with that. In good weather, and with a clear route (like a groomed ski trail), sure. But in a blizzard at midnight a mile is an awful long way. And I am talking about a first time. If you are cold and it's getting colder and you don't know what to do to get warmer, and you are not with a more experienced person who can help, I'm not sure how much more you're going to learn by sticking it out. You already know you're doing something wrong or have brought the wrong gear. And the distance from uncomfortable to dangerous is very short in the winter.

Some of the North CA group I bp with and myself have had to snowshoe out from Lake Winnemucca on the Carson Pass after 2 feet of snow had dumped on us. Not so bad in the more open areas where the wind blew half of it away, but in the sheltered meadows, took 40 minutes to go 100 yards thru near waist deep snow. I, being the oldest got to break trail for the younger crowd, no one offered to spell me. Then the SnoPark we parked in had not been plowed, so after shoveling all day, we left close to 5 that night.
Duane

... done that several times.

But now that I'm a geezer I think I'll do it only when I carry a SPOT beacon. Too many truly experienced hikers have died in the outback near Las Vegas in the past
several years due to plain ol' accidents like falling, etc.

Seems fate does not aleays recognize experience. And then there's always Murphy and his cousin O' Toole.

I tend to go to higher elevations in November and April/May - 10 to 11000 feet - still can be pretty wintry. In the coldest months, December through March, I enjoy myself more if I stay at midelevations in Colorado - 8000 to 9000 feet. It is best when snow is on the ground. I have to admit it would be tough going without the campfire to take the chill off in the evening and early morning.

I go solo but take a spot GPS in case of an emergency - probably will never have to use it. I have found that a small tent holds my heat and my border collie's heat - makes a real difference. I also use an inflatable mat to get up off the ground.

This Thursday is a full moon - the best time to head up in the winter, considering the 14 hours of darkness.

I solo backpack all year round in Labrador, Canada, including winter, and then mostly snowshoe hiking. Practical safety always applies: a means to signal if necessary (DeLorme InReach for me and pen flares); suitable clothes and shelter to stay warm and dry (especially in winter if you get storm bound for days); and food. To accomplish the last two my base weight goes up considerably in winter. Coldest I've slept out in is -24C/-18F without wind chill.

As to avoiding number 1, the need to signal for help, your risk increases dramatically when you lack local knowledge of where you are hiking, especially in remote areas where there are no other hikers or passers by and you are plodding around on snow in places you have never been. Going solo will always entail greater risk, and consequently demand greater care and caution if you wish to be safe.

The gear you need is very context dependant. What works in a New England winter might be wholly inadequate in northern Canada, and vice versa. Likewise between trail hiking and backcountry expeditioning.

There are no magic bullets.

Good luck!