Different manufacturers use differing methods with cabinet fit-outs - many do use cabinets/furniture as an integral part of the strengthening of the "house".

Most of the composite walled "plastic box on wheels", build the box, then furniture/flat pack are fitted. Note most of these have their electricals under/behind this furniture as opposed to framed vans that have wiring within the walls.

I suggest prior to removing/altering furniture; you take a tour of the manufacturers factory - even a U Tube video tour to note their manufacturing methods.

Almost every manufacturer build one off's even on Models appearing to be similar - very few can supply wiring or plumbing drawings because of this individuality.