Jake, your comments jogged my memory about something that a lot of people intending to renovate a mobile home might not know about how such homes were built. A few comments might help even if they are only mostly true about most mobile homes.
Conventional homes are built from the outside in more or less.:
A foundation is established
A frame is put up
The frame is sheathed and roofed on the outside of the structure
The insulation is installed
the electrical wiring is installed
The plumbing is installed,
the walls and ceiling are sheet rocked
Paneling may be added where desired
The walls ceiling are painted papered textured and painted
The floors are tiled carpeted or vinyl laid down
Pretty much in that order, more or less
Not so for mobile homes which are to a great extent built from the inside out. following a general plan more or less as follows, (varies with different companies).
A steel frame on axles is built
The floor is built consisting of framing in both directions (stringers lengthwise and joists cross wise) with the framing sometimes assembled upside down.
Plumbing heat ducts are run lengthwise or cross wise through the framing.
Insulation is added,
celllulose fiber board is secured in place over the insulation. and the whole thing turned over so that it is now right side up. and placed on the steel frame.
The floor structure is attached to the steel frame.
If it was not done previously the flooring boards (e.g. oriented strand board, (aka OSB) or plywood )is added.
Floor coverings are added.
Pre cut exterior wall studs are fabricated with an array of notches for electrical wiring and used to build walls that are panelled on the inside with window openings pre formed.
The exterior walls are placed as units and secured to one another and the floor structure and in some cases the floor framing in a unique manner that may resist transport loading better.
Interior wall framing made in a similar manner possibly panelled on one only one side is added.
Insulation is added between the exterior wall studs.
A "wiring harness" may be used or individual wires may be run with the wires indiividually and outlets connected up through the walls. with wires run into the interior walls for switches outlets and fixtures
Interior wall paneling may be completed at this time.
Furnace,
water heater, cabinetry plumbing fixtures may be prepositioned at this time.
Roof joists put in place at this time and ceuling panels secured in place and light fixtures installed and wired.
Exterior siding of walls installed
Windows installed
One piece sheet metal roof installed over rafters and bent down at the edges to be secured to the header of the wall framing. including a very small Aluminum J-Channel to serve as a rain gutter of sorts into which the edge of the roof is bent down.
An array of finish installation tasks are performed.
DISCLAIMER: while I have not worked in a mobile home factory, I have worked on multiple mobile homes where these structure features are visible and I have been informed by others, and the precise sequence used in any factory or by any manufacturer may vary. A variety of differences exist and some are structurally superior for resisting transport loads and other are not so good and may require things to be fixed after transport (e.g. panels that were only stabled come off of walls. some manufacturrs have used superior methods for attaching the exterior walls to the floor structure, some manufactures may have used glue between wall studs and paneling and not just staples. etc. etc.) The foregoing is only intended to be only representative of construction techniques and sequences .
That being said, It should be obvious that there are profound differences, so that when upgrades and repairs are done different and sometimes difficult techniques have to be used. If the home is in a really hot climate and air conditioniing needs to be added via a window mount unit, there may not be enough structure in the wall to support it. Putting a separate support to the ground may be a very poor choice for a trailer on pilings as these often move do to wet/dry cycles and frost heave. and the trailer may move relative to the AC support. Exterior reinforcement of the wall with treated lumber may be highly desirable. Adding a
wood stove for heating can be a really dicy operation and needs careful planning. I MEAN REALLY CAREFUL PLANNING !!! (I can recount two different techniques I used.if anyone is interested. It was a conventional "jackeded" wood space heater. It was not a
rocket stove, so I cannot speak directly to that. My first installation was safe, my second one was also much more convenient)
An important point is that the construction code for mobile homes is based on climate zones so you do not want a home for the southern zome if you live in the northern zone or you wont like the heating costs. This may be less of a problem with newer homes but a big one with older ones.
My whole point being that mobile homes are very much a different beast than conventional homes, so please have your eyes open when considering this option. A mobile home can work well as a solution but they "tend to be shorter term solutions" but not always so if done right. I should also add that they are prone to some unique and curious problems which are only correctable at reasonable cost by using careful diagnosis and clever solutions.