Most of the comments on here about the costs of owning a boat seem to be comparing with having a mortgage (presumably from people who have or had a mortgage). If comparing with renting then the equation changes somewhat. I'm certainly not ignorant of all that - I used to have a mortgage, paid it off, but my ex now lives there, so the alternative to living on a boat for me was renting. My current financial situation wouldn't allow me to get a mortgage, however I am in the fortunate position of having plenty of capital (though not quite enough at the moment to buy a house with cash), hence I could afford to buy a decent boat - my attitude is that it might not appreciate like bricks, but if looked after properly neither should it depreciate significantly, hence it's an asset. I've read lots of comments on here, done the sums again and again and I'm still convinced it's far cheaper than renting, at least for me given my circumstances - a single bed is no use to me as there's no space for my kids (my boat has a second cabin for them), hence I'd be looking at £800+.
Of course it does all depend on your exact circumstances but as an alternative to renting, living on a boat certainly can make financial sense IMHO.
I've never hired a boat either - instead I started living on one in winter! As the OP discovered, hiring can quickly eat up a lot of money compared to buying - even at long term winter rates. I suppose it depends on how prepared you are to take a risk - but not only on that but also what other experience you're coming in with. The OP mentions that he's happy with camping and that living on a boat would be a step up - in that case he's unlikely to have big problems with the living conditions in winter IMHO. That was one of my considerations when I decided to get a boat - I don't need luxuries (though as it happens I have plenty on my boat) and happy to cope with all the stuff some people seem to think is difficult. Sure I might have only been living on board for 3 months and have a lot of winter ahead, but I'm nowhere near my discomfort zone at the moment despite several nights of frost - TBH it's not really anything like camping, it's far easier than that, but coming at it with a camping attitude makes it all seem fine.
The other point you mainly cover is the moving a boat aspect - I'm not sure how much of that the OP is planning on doing, but again I've found it nowhere near as hard as some seem to make out - certainly not if you're young and fit as I'm guessing the OP probably is (I'm not so young myself, but way fitter than most 20 year olds). I gained my basic knowledge of steering and working locks on the first day I owned my boat! Well that and through doing a huge amount of research in advance, and a lot of experience of sailing dinghies which helped a lot with the boat handling.
Personally given my circumstances there was only one possible option of where to live - my whole voyage started when I found there was a mooring available here. It is indeed the most important thing, I didn't commit to buying a boat until I'd got the mooring confirmed.
Again it depends how confident you are about doing new things like this - my trip to get here was 80 miles and 130 locks and took me over a week single handed. The first time I'd ever driven a narrowboat was when I had to get mine out of the marina where it was moored (which is still the hardest thing I've ever done, it's way easier getting in and out here). The first time I'd ever done a lock was about an hour later, the first time I'd slept on one was a few hours after that. Most people probably think I was a bit mad, but I made it here without any major mishaps and now kind of know what I'm doing. I'm so, so glad I did that - it was an adventure with a purpose which I'm never likely to repeat.
It is sensible to set a limit on range when looking though for practical reasons - that was about the furthest away I was considering (though plenty of choice within that range for me).