Actually I was wondering too if a possible next step might be something like this (mentioned in post quoted above)? Brand ‘Raynor Winn’ is primarily the narrative of a journey in nature, overlaid with a negative ‘redemption’ theme - eg homelessness / terminal illness / marital insecurities.
She could very well continue this theme with a journey in nature (maybe overseas?), where the overwhelming negative / redemption theme is the notoriety / consequences of previous bad decisions they have made.
Instead of people they meet hurrying away because ‘they are tramps’, they could be hurrying away, or being hostile because of the Walkers’ bad decisions / deceptions / notoriety... the book could explore how they come to terms with this as a couple, and individually, and as members of a wider family… and could feature flashbacks (and fore-shadowing?) of the events that have previously happened re: the writing of the books (probably intended as something inconsequential, and possibly anticipated as giving them a small lump sum) and the subsequent snowballing into becoming very high profile… and why they mistakenly (and understandably?? / foolishly??) chose the path that they did - and about how things have accumulated, and compounded, and reached a crisis point.
In fact, there is a large amount of potential foreshadowing already, which can be included in the new book… the whole episode of the (starting small) alleged thefts that snowballed to the stage that she was shocked to learn they were £64k, which then snowballed (through bad decisions) to evading the law and taking on an eye-wateringly bad debt (who on earth would accept those loan terms unless they were a fool - or desperate).. which then escalated to massive increase in amount owed, loan foreclosure and loss of their house.
It is almost like the cycle starts again! And obviously these flashbacks and foreshadowing can really explore the human side of what it is to make the worst decision possible, in any given situation, and having to live with the steadily worsening consequences of that for many years afterwards. A big dollop of humility - and some stirrings of a blossoming self-awareness and a newly-fledged sense of empathy, and it could be a successful (and redemptive!) book, that continues to reinforce the nature-tragedy-redemption brand…??