Not a construction expert, but the consensus is that La Casa isn't salvageable, right? Cheaply-built mobile home, not decommissioned properly for high temperature and humidity, left abandoned for years to warp and mold.
Given that it's been sitting, essentially abandoned, in a humid climate, proper mold abatement would be impossible without throwing far more money into the project than the trailer is worth. They'd have to gut it, and start over.
Even the cheapest methods I can think of to mitigate the problem (cleaning every surface in the place with bleach, before sealing the floors and affected walls under multiple coats of varnish, then painting and laying new flooring over it, plus having all of the ductwork thoroughly cleaned by a pro with the right equipment) are going to be so far outside their budget, we might as well discuss the viability of Polissa's artistic career, too—because we'll be that far off in La-La Land.
To think: had Auntie decided, all those years ago, to get the walls fixed and other repairs made, and continued to live in the trailer, it
might still be habitable. Instead, she retreated to her mom's house on the same property, and just left the whole thing to rot. It was a mess, but it was still a functional structure when she moved out, and now it's not worth salvaging.
Where were all of those men in the family—the ones who were supposed to help Polissa and Josh fix up the even more dilapidated, long-neglected trailer—when Auntie needed them? If she is, as Polissa described her, this good-hearted woman who tried to do right by taking someone else's kids in, who then trashed her home, why didn't anybody step up and help repair the damage once the kids were gone, so she could move back into her own home?
Polissa and Joh probably can't swing a tiny home (built by others), or even a small yurt. As much as I would love an attempt at a geodesic dome kit or a straw-bale house, I think their best bet would be towing out an RV with functioning living quarters, or (Joh only) a pre-built shed.
Any form of housing that is provided for these two will end up trashed due to their laziness, stupidity, and animal hoarding. The only way that won't happen is if they get into Section 8 or public housing where they are allowed no more than one or two pets, are subject to regular inspections (with clear consequences for failing to pass them), and there is somebody else to do needed repairs and maintenance.
And living in an RV is not a solution, because (with rare and expensive exceptions) RVs aren't built to serve as full-time housing. A typical low-to mid-priced RV or travel trailer is going to go to shit really,
really fast with people like the Campbells living in it.
A dwelling built of cinderblocks, with every surface covered in non-porous finishes, and floors that slope to drains in the center, might be able to stand up to them, but you'd still need a construction debris box and a biohazard cleanup crew to come through and deal with the mess after they were gone.
The truth is, they are both too incompetent at life to live without somebody there to stay on top of them, keep breaking their inertia, and prevent them from drowning in their own inevitable squalor. They've got the most fucked-up version of the Midas Touch, in which everything they touch turns to shit, and none of the housing options that might ever be available to them are safe from that.
what state does pissa live in again?
sights 
At least we can laugh about it, and that's something to be thankful about. Who knew something so terrible could provide so much amusement?
in the world to all the farmers thinking bumfuck nowhere rural alabama has an HOA checking for shit bag contamination, animal welfare that will pull out fainting salts at the idea of feral kittens, and the majority of the townfolk aren’t the hills have eyes living in trailers one step above la casa.