This book should be renamed "How to Pay Someone Else to convert your (mainly)T5 to a camper, while you take a lot of photographs."
Nearly everything is 'off the shelf,' from & fitted by a manufacturer or agent - And done well - but it's not DIY as implied & few of us have that sort of money.
Lot's of - 'don't try this at home/get a registered Corgi/Electrician/Converter' to do this for you (though you could do a bit, though we're not going to tell you how...)
There are almost no useful diagrams or schematics for the water or electrics. No dimensions for units, directions for cable runs. Nothing about fitting your own rock&roll bed, seat belts, carpet lining...The list is sadly endless.
If you are doing a DIY - look at both the Build your own Motorcaravan & the Motorcaravan Manual from Haynes by J Wickersham - While these are not VW specific, but they treat you as an adult & have information you can use!