Evicted Family now Smell Remains

My 92 Mustang GT was parked up for a few months while I rebuilt the engine bigger, better, stronger (we can rebuild him, we have the technology). In this time a nomadic tribe of mice happened upon my car and after some scouting noticed that the shifter boot had been cut and allowed free access to them and the outside. So in they pooped and proceeded to have loud parties and generally abuse the place. Fast forward to last month when I was checking the car over getting ready to move it to install the new engine - the smell was a real neck breaker - I left the doors open for awhile and the smell seemed to go down to a mere neck sprain. One of my friends advised that I put some mothballs in the car because mice hate the smell of them. So I dutifully emptied a box of mothballs over the seats and carpet and closed the doors for the week, ready to come back next weekend to a car that smelled like fresh flowers. Imagine my surprise when I opened the door to a smell of mothballs AND mouse pee - I swear they could bottle this and use it as a new weapon. Checking over my shoulder for any UN weapon inspectors I removed the seats and vacuumed everywhere - used three bottles of pet stain cleaner on everything and it was all nice. I fitted the engine and closed up shop for the week. Next weekend I came back to a fairly toxic smell of mouse pee, pet cleaner and a slight smell of mothballs.
HELP!
Is there a magic technique I’m missing here short of ripping out the entire interior and replacing it?

I would try stream cleaning with a solution. Check with carpet cleaning company for recommendations on brand of solution needed.

I was trying to avoid removing the entire interior, but I guess it’s going to have to be the case. I know pee is very corrosive and I think i’ll coat the floor with a rust inhibitor then replace the carpets - seats are the easy part.

Are you able to remove the carpet and then clean it separately while also dealing firmly with the exposed floor pan? I would talk to a professional cleaner (you know, the guys who clean up after fires, sewer back-ups, people dying unnoticed in their homes etc). It’s not mouse pee but my vehicle was previously owned by two very heavy smokers (four to six packs a day between them). While they didn’t spend every waking hour in their (now my) truck, to a non-smoker the stench of stale nicotine was overpowering. I cleaned the bejeesus out of the carpet and the headliner (somewhat gingerly to avoid wrecking it). Thankfully the leather seats responded to a wipe down with a leather cleaner and conditioner without issue however the door panels, carpet and headliner still stank. Being in the insurance industry at the time I knew someone with an ozone machine and after leaving that sucker (designed to remove the aforementioned unpleasant smells from entire houses) shut up in the truck for two days, presto, stink almost entirely gone. I say almost because for some time thereafter on a hot day, if left parked in the sun with the windows up, you knew the truck had been smoked in. Reminds me of the story (probably apocryphal) about the guy who got an absolutely incredible deal on a late model Corvette. Turns out the previous owner had died in it and on a hot day it smelled like a trench in the Somme in mid July 1916…

You need to kill the suckers before you try working on the smell. It sounds to me like the rodent problem isn’t solved yet. I would put some rat poison stations in there and let them do their job. Then worry about the smell.

In case the OP is not aware of it, the remaining odor is just the tip of the iceberg, so to speak.
I am referring to the very real possibility of contracting Hantavirus from the mouse droppings and urine left behind in the car. If you think that this risk is something that is exaggerated, I suggest that you take a look at:

At one time, medical authorities thought that this danger only existed in the US Southwest. However, the death of a young man on NY’s Long Island as a result of Hantavirus changed their thinking on this disease threat.

Personally, I wouldn’t fool around with the existing carpeting and upholstery. If I were you, I would don a high-filtration dust mask, strip and bag the textile-based interior parts, and then sanitize the exposed areas with a dilute bleach solution. Then, wash your clothing in a hot water and bleach solution and shower very thoroughly. Hantavirus is not something to take likely.