Spot on G.
When dad and I go to Glastonbury, it takes us approximately 5 hours to set up our T25, awning and all of it's kit to how we want our pitch to be. I've seen people even in the huge bus sized homes take several hours.
An additional thing is the fact that most fridges and heating systems in motor-homes run on gas. Running them from electricity draws way too many Amps and without a running engine, even the biggest leisure battery would be dead pretty damn fast. In order to run, they need to be level. In a wet field or on a slope, unless you have some serious self levelling suspension and extending support platforms, it's damn tricky! Also, trying to cook when all the oil in your frying pan is tipping out of the side and down your front isn't fun.
We've developed a special piece of kit with several spirit levels that tells us when the vehicle is level, however you still have to spend a while chocking up, jacking, altering heights and using levelling ramps to get it level.
There's no damn way that if I went on holiday in the van I would want to be doing it every day. Once for a week's stay is damn well enough!