I doubt you will get many responses here from folks who "actually live on their bikes and it's their only way of life".
I have done a little touring in winter and it was limited to the southern US, but the only folks I have met who I'd actually consider as full time were more likely to be categorized as homeless folks who bounced around a little by bike. Most of them were on the Pacific Coast and it would be a bit of a stretch to call them tourists IMO. Some were more mobile than others. At least one said he went back to where he had family once in a while and worked for a month or two to make a few bucks to live off of for a while.
One guy was living on the road with his dog and stayed in the Southern US in the winter. I got the impression that while he had logged a lot of miles he tended to stay put a while pretty often. He seemed to have been in the campground where we met him for a few weeks.
Another guy who wasn't a cyclist was "walking across the US". While it wasn't bike touring there were similarities. He started out with a a goal of walking to the west coast, but somewhere along the way decided that getting there wasn't the goal. He had been on the road for quite a few years and was likely to be for quite a few more. His M.O. was to get stalled in one place for months (years?) at a time if he liked where he was. He was camped in a $10 a night campsite at an indian reservation casino in Arizona and had been for some time. That was 2012 and I wouldn't be shocked if he were still there. They had showers and good food for cheap. He had a double wide baby stroller to haul his gear (very nice gear by the way) and was living off of his social security checks via a debit card which his daughter saw to managing for him. I ate a couple meals with him while I was there and enjoyed his company. He was an interesting guy.
That is about the extent of my actual experience with folks "full time touring". Others that I have read about generally did not limit themselves to one country, but rather travelled more widely making seasons less of an issue or possibly a non issue if they wanted to.