However, looking at a later posting I read the suggestion that in the lower 48 USA States you could get enough natural exposure (there is an argument about Washington state/Seattle) but surely in the mid west you have winters so severe that body exposure would be suicide and in the summer body exposure would result in a dehydrated crisp
People can, and do, get sun burns while skiing. As to winter sunlight exposure in general, I wasn't really commenting on it one way or another, although "Sun rooms" are a thing as well. They're basically "glassed in" rooms not much unlike a greenhouse, where thanks to being enclosed, the temperature can be controlled. From there an occupant can sun bathe, or not, at their leisure.
My main focus was on the more temperate months and summer, where it then just becomes a matter of limiting your exposure and being properly prepared. Typically speaking, in the summer months in particular, 15 minutes outside sun bathing per day is likely to be more than enough. And a lot cheaper than visiting the doctor multiple times a week for "clinical services."
That and 50°C(122 degrees for us Yanks) isn't that difficult to survive, particularly if you're next to naked and keep yourself well hydrated(sunscreened up if not deeply tanned already, etc). Now if you're dressed like it's 12.7°C(55) and it's that hot outside, yeah, you're going to suffer. Of course you could go the Arab route and put on a couple layers of light, flowing clothes that do little to restrict air flow, but a lot to screen sunlight...
I should add that I was one of a multitude to get skin cancer (mine was mild and easily treated but most were not - two friends must avoid sunlight for the rest of their lives!)
From what I'm hearing, the universal correlation for skin cancer seems to be Sun Burns, not so much sun tans. Particularly when you look to the two major types of skin cancer. Which is where they're starting to correlate information in some other ways.
The most easily treated form of skin cancer typically happens on parts of the body that have seen a lot of sun exposure(which I imagine was the case for you).
While the more difficult to treat cases tend to happen in places that can get burned during sun bathing for example, but doesn't generally see much sunlight otherwise due to shirts/pants/etc.
Also keep in mind that with skin cancer and Sun Burns: up until the 19th Century(and the 20th in many places) the most extreme case most people would encounter is maybe 1 sun burn per year. Because after that, they developed a tan which protected them from thereon which they maintained for the rest of the season because they mostly worked outdoors.
Now move to the present day, where some people can experience(/self-inflict) a sun burn multiple times in a month, because of all the time they spend indoors. And now wonder at the rates of skin cancer being witnessed.