Wow, you got it bad. At least the mice I had were mostly dead, I think the live ones went into my house.
When I bought my car it was in a barn in New Hampshire. My brother in law wouldn't even go in the car because of the mouse urine smell. Rascals took the seat cushion material and made nests all over. If it wasn't for wanting to clean out the mice, I wouldn't have found my buildsheets, although they ate up one pretty bad.
Places where ther were in my car:
-cowl- the worst because now I have a cowl leak from the water that was dammed in from the mouse house.
-in back of rear seat
-headliner-poke the headliner, if it feels firm, it's a mouse house
-inside the area where the rear window crank is above the rocker, in front of the rear wheel.
-kick panel area
-any place between the air intake of the cowl to where the lower vent area is where the air blows on you from the vent under the dash.
-sides of trunk
glue boards didn't work for me, moth balls seemed to work.
Seal up the exhaust and air intake of the air cleaner.