You might be interested in this link, too. https://www.britishhedgehogs.org.uk/pdf/Hibernation-Weight.pdf
Where, if you scroll down you will also find reference to adult hedgehogs sometimes needing over-wintering too, with photos – similar to what you mentioned – of a nicely rounded hog and thinner, longer, underweight one.
I agree, there is a lot of conflicting advice out there. You have to be a bit discerning, but it is usually possible to navigate a way through, I find. I always think BHPS is a good place to start. As you suggest, a good dose of common sense comes in handy – as well as a lack of stubborness and defensiveness. I also agree, there is always more to learn about hedgehogs, but suspect they will always retain a certain element of mystery.