These have 50mm insulation in the walls and ceiling and the wall and ceiling linings have cavities in them which makes these relatively quite inside compared to the insulated panels with steel both sides.

Floor is ply with woodgrain look vinyl covering. While these seem fairly good for retaining heat you could add underfloor insulation if you felt it was needed after arrival as the underfloor and chassis is accessible simply by jacking them up.

If the unit has a toilet/shower and sink then there is an inlet for cold water, an inlet for hot which can be piped or from a gas califont for as little as around $200 on Trade Me. Shower and sink have a smaller pipe lower down by the chassis and the toilet with the large hole near water inlets. As well as direct pluming into your system you can get a cheap tank with automatic pump and macerator for well under $300 on Trade Me that can pump through a flexible caravan hose quite some distance horizontally as well as vertically.