I think this is a great idea as long as you break it into appropriate sized chunks, which it sounds like you intend to do. This could also include a "master Q&A" pitched on a higher level of abstraction that refers to various component tasks in other Q&As.
With regard to topicality, as I and others have noted here before, our overlap with U&L, SO, and EE is such that if we were very vehement about it, the site would not be feasible because there would not be enough "non-gray" area left. We are hardly the only SE site that overlaps another, of course, and some sites, rather than rejecting questions that overlap with other sites, encourage it. So the network leaves it up to individual exchanges.
The reason the policy has evolved this way here is because it allows us some room to limit questions, meaning the truly significant issue is not enough people to answer them, or people without the expertise available on other sites. It's a disservice to people in need of such help not to migrate or close as off-topic.1
The realm of the self-answered question doesn't suffer this problem, presuming the person who writes them knows what they are talking about and can communicate that knowledge effectively. From what I have seen of your work, this is not an issue; I believe you know what you don't know and you also are good at research and practical implementation. You are certainly one of the most valuable contributors here over the past year, and more from you is always welcome by me and I am sure other member of the community would echo that sentiment.
- This discretionary enforcement of course leaves room for unfairness. I've always been open about my inconsistencies with anyone who cares to ask. But, although I think it has happened, I honestly cannot recall anyone complaining "If you closed my question as off-topic, why didn't you close this one?". In general the questions that are closed this way have other problems beside topicality, which is why I usually do not migrate them directly to somewhere else. Conversely, I'd observe that some migrations by other mods on other sites occasionally appear to be intentional off-loading of just plain junk.