From reading a thread or two of people doing this, building their own trailers… You will need to treat it as a brick and mortar build in some areas. Call in the building inspectors as well as the health department. But this would depend on your area I guess and your health department. I would check with your local health department first before doing anything.
Yes all the proper local and state agencies will be talked to. However they can’t answer every question. Especially as to whether or not it’s worth it to build my own or buy something used. Plus they can’t offer me real live experience. They can offer codes that must be followed.