The interesting thing about the Prius is it can also be used as a gasoline generator with a plug out conversion kit (still far quieter and less polutey than a standard genset). That could save your bacon if you find yourself without site power and one battery charge short of completing the job. In fact you could probably charge a few batteries off the Prius HV battery without need for the ICE at all.
Buy an all aluminium trailer, the Prius is only intended to carry 800lbs all up (driver and cargo). Alu trailers in a 6x4 start from around 160lbs.
I've thought about converting my Prius for work as well, but I'd go with something more like the Prius camper:
https://www.google.com.au/search?q=p...KcWq0gTG-Z24BQ
But a bit less extreme.