Let's improve the Mobile Home.

How I would design mobile homes...
No wood, and no plywood or fiberboard--- Start with a steel shipping container. Same size as a mobile home, WAY stronger. Generally about $2,000-$3,000. so it wouldn't raise the price too much.

Mount it on wheels, but add drop-down lockable steel legs, like a trailer on a 16 wheeler has. None of this stacking up loose cinder blocks. Make it so the wheels can stay on, too.

Pex lines for the water. run them INSIDE the trailer, along the baseboard where you can get at it easily. Not everyone can crawl under a house to fix a leak, and frozen pipes are a nightmare, especially for someone poor enough to be living in a trailer.

Run the electrical wiring along the edge of the ceiling. Again, you shouldn't have to rip out your walls just to fix or update your wiring, or your plumbing.
Keep that stuff EASILY accessible-- hide it behind a cover if you're fussy, but really...

Forget skirting, the skirting they make is flimsy crap that tears right off in a high wind. It should be a crime to sell that stuff. A trailer should have built-in drop-down panels all the way around.

The worst part of trailers is they are so horrible for climate control--- an icebox in the winter, a solar powered roasting oven in the summer. You spend a fortune on power not merely to be comfortable but to even be able to LIVE in your home. As in, it could literally be FATAL to try and live in a trailer without an AC. Let's FIX that.

There should be a second roof or awning, just a foot or so above the actual roof... a sort of mini-attic space. Makes room for insulation, plus that gap means you don't have the sun beating straight down on a black shingle roof in the summer. put a fan at either end of that gap and it becomes a breezeway, keeps the house even cooler. Put a second set of fans UNDER the trailer, for double the cooling.

it should include a solar preheater for the water. Just some looped copper tube painted black in a sealed flat box, with a glass pane for a lid. Feed the water line in one end, attach the water heater to the other, and put the panel on the roof. The sun will heat the water before it enters the water heater, saving hundreds of dollars in electric or gas even in winter, for maybe 100 or so bucks in plywood, glass, copper water line and paint. It could even be adjusted to help heat the house in winter, with a few dozen more feet of line running to a copper pipe radiator inside.

Electricity stopped being a "luxury" ages ago.If you run gas lines, the trailer should include an emergency electric generator that can run directly off that line, or off a propane tank. That way if the lines go down, you still have power in your house.

Windows should be double paned and of a manageable size. Huge picture windows on a trailer don't help; they let in light but they also let heat IN during summer and OUT during winter.

For better lighting, there should be shuttered skylights in every room, or even just one running the full length of the trailer. There are ones that are two frosted half-globes connected by a flexible tube of reflective foil, so you could put one on the outside roof and connect it to the globe on the inside. Either way, again an electricity-saving measure. They do this in 3rd world countries with soda bottles filled with water stuck through the ceiling. A trailer should at least aspire to something that works that well.

No fake wooden paneling. It's ugly, you can't do anything with it, and it's DARK which means it makes it harder to light your home. Let it die in the 70s where it belonged. The interior should be in light colors, and paintable surfaces.

Put the bathroom, kitchen, and laundry fixtures as close together as possible, all at one end of the trailer. shorter water lines equals fewer problems.

A small woodburning heater should be included as well. More options in an emergency is better all around.

Both front and back doors should be double wide. People gotta get furniture into and out of these things, after all. Since we're starting with a shipping container, keep those big double doors at the end. Simple stairs or accessibility ramps should be a must as well-- they don't need to be fancy, just STURDY. Build them out of the stuff they use for fire escapes.

Bathtubs are notorious water wasters, and they're ruinously difficult for the elderly to climb into and out of-- a major mobile-home-owning demographic. A walk-in shower with a sit-down bench or stool should be standard. In fact, waterproof the whole bathroom and put a drain in the floor, Japanese style. Put a reversible ventilation fan in, to speed drying. Put a ventilation fan in the laundry room too. Recycle heat from the dryer to help warm the house in the winter. Heck, floor drain, ventilation fan and waterproof floor in the kitchen too.

Fire, smoke and CO2 alarms, and a sprinkler system should be built right in. We put them in warehouses, they can't be too expensive. Gas leak detectors would be smart, if they make such a thing-- Why aren't these things a part of housing construction automatically anyway?

Burglar alarms. BURGLAR ALARMS please. Even if nothing more than a panic button attached to a klaxon. Nothing needs be expensive at all-- just a contact switch on the doors and windows attached to a bell. No house should be an easy mark.

Wall-to-wall carpeting... should be left out. Let's be real, people; the stuff is the worst fad of the 20th century. It's dirty, it's nasty, it gets stained and vile it harbors dirt and lice and mold and fleas and it stays filthy FOREVER because it's officially impossible to properly clean because you can't pick it up. Yes it feels nice on your bare tootsies, that's a stupid reason to cover every floor with a filth farm. The only reason it's in mobile homes is to cover the cheap junk they use for flooring. There's wood paneling, there's tile, there's vinyl, there's plenty of inexpensive options and they'll save you costs to your wallet and your health in the long run, and throw rugs look MUCH nicer and are far more stylish.

Glow in the dark light switches. likewise glow spots on doorknobs, drawer handles, spigots, hallway corners, etc. Trivial and silly sounding-- till the lights go out in the dead of night and you gotta pee.

Come to think if it, a glow in the dark toilet seat....

A 50 gallon steel drum for a built-in back up water cistern. Easy to use shutoff valves-- not spigots, knife switch style--- at several points in the house. Likewise for the electric system.

Note: Nearly all of the above changes are low-tech, many are things that amount to minor changes in layout and materials choices, several are long-term money SAVERS and all of them improve the safety, comfort and durability of the typical mobile home. And seeing as you pay almost as much for a new mobile home as you would for a "proper" house these days, the costs of changes are negligible. Handyman types feel free to run the numbers and tell me different, but when people everywhere are building microhomes for less than the cost of a used car, I suspect I'm more than right.