Toilet is critical. You will need it (knew a friend that decided to not install one and rely on public loos while staying at a ski resort...lasted two weeks.) It's just that you don't want to take a dump unless you absolutely need to. This is less to do with then, but more when you need to 'empty' the waste. You will be peeing and you can either do that in a lay by, but with snow on the ground and 3 in the morning....then somewhere to pee in the van that also can be 'sealed' to contain the smell is critical.
Mine looked like this: http://www.carandclassic.co.uk/uploads/cars/land_rover/30328...
Going for swim acts as an opportunity for showering.
It's great fun after you get over the initial shock of creature comforts requiring planning and thought.
I eventualy gave in I found that the chassis had a huge hole in it and I had to start putting in as much oil as fuel.
Must admit it's a pretty good way of living but not sure I would do it for years on end.
Now canal boats....now that I could see myself doing one day.
I'd do it again, 100% of the time but the three children, wife, mortgage and inevitable responsibilities that come with these things make it difficult if not impossible to achieve.
Narrow boats and widebeams are horrid. I lived in a narrow boat for a month. They rock very slightly, smell awful, are damp as anything (even the nice ones), cost a fortune to keep afloat and the neighbours aren't particularly nice people I've found. Very clicky, suffer from a major superiority complex and are terribly bureaucratic. Thames barge perhaps but narrow boats; never again!
You might enjoy it, but I certainly didn't.
Also, literally everything went rusty. Even stainless steel and my windows mobile 5 phone at the time went rusty.