Pressure washer has a very high chance of getting water into parts that cannot deal with it. Just use a hose and a brush, works great.
If you do want to risk it, a pressure washer requires a not insignificant amount of energy, so you will either need a very big inverter + instalation (big cables) or a questionable 12v washer or a pressure washer that runs on petrol.
Or you just get a tank of water, a 12v low pressure pump (camping/boat) and wash it with low pressure and a brush.
If i was looking for a way to wash my bike before transport, that is the way i would do it.