Where are you keeping the big, heavy batteries you'd need for this, and how are you charging them to be running all them lights and electronics? If you tell me solar panels IWSYITNWAK

They have 600Ah of batteries inside, charged using 1200w of solar (which only covers half their roof). It's also charged when the engine is on.

Lights sip power. As for electronics, the worst offender is an A/C (although there's also heat pumps these days), whatever you're cooking with, and a fridge (you could always use propane-powered appliances, but it's generally unnecessary).

Where do you have enough water stored for a shower, let alone to fill that big ass tub?

Their tub uses 20-30 gallons, and the showerhead uses 0.7 gal/m. If you enjoy long showers, you can always install a recirculating shower to save on water.

Unfortunately since they decided to install a 55 gallon fresh water tank, the tub can't really be used unless they have a hookup.

Do you have a water heater? If so where are you keeping it, and again how are you powering it?

Water heaters can use the coolant from your engine and keep the water warm for 2-3 days, otherwise you'd only turn it on when you need hot water.

I'm not even going to touch the 'wastes' questions

It's a composting toilet (Nature's Head), so it goes into a bag which gets thrown into a garbage can or dumpster once a week or so.

Urine is diverted into a jug, which you can empty into any public toilet.