If you can smell mouse pee on the bare and cleaned metal, clean the rest of your work area up and make sure you do not have any mouse pee debris laying around and move your metal into a different clean room or outside air if it is dry outside.
If you have to clean and paint again.
If you have the seat frame and springs in your truck it is likely that the smell is coming from the rest of the truck.
Strip that stuff out and clean it up.
If you still smell a strong odor, look at the wiring and material under the dash.
This may seem like a slightly OT example, but I saw a auto customizing program not long ago that featured an AMC full of rat turds.
The workers found the rat that was producing the feces way up under the dash board on top of the heater vents.
This was a big rat, not a mouse.
Reminded me of my junk yard adventures.