Although I have seen and used this book, there have been a lot of changes in the past few years, and unless he has major updated it in the last few years, I would like to see more recent information. However for DIY stuff, most of the general concepts haven't changed, so it is really good to give you an overview of systems. Just don't be suprised to how much things have changed over the years.
If I were a few years younger, I think one of the RV Tech training schools would be a great idea. A good well-trained RV tech that doesn't mind working should be able to do well in this day and time.