rodent odor problem in my 69 cuda
Regarding your cowl. Since you have interior out and heater core assembly out?
You can access the cowl area marginally thru the air tunnel holes on each side under dash. I would flood the cowl with boiling hot soapy water in 5 gallon buckets thru the inlet front of windshield. This will dissolve turds and urine. Follow up with a very dilute 5 gallon bucket of bleach water. Like a cup of bleach in a 5 gallon bucket. This will sterilize any remaining debris. Then pour a 5 gallon bucket or 3 of pure water thru.
Then take air hose or a leaf blower and blow down thru and up thru cowl from under dash. The cowl on mopar drains to fender area near lower door hinge. Crap may be collected in this area too. It is usually chock full of misc crap and rat nests.
If your cowl is full of nests, they will clog the cowl drains which lead to inner fender just in front of door hinges. Problem is, impossible to access w/o removing the fenders I am pretty sure. This will just suck *** for ever, having clogged cowl drains, lead to rust and smell.
Take bolts out of bottom fender near door hinge, remove a few inner fender bolts and pull the bottom of the fender out and prop it open a few inches. Use leaf blower or air hose to expel all debris and any moisture. Leave lower fenders propped open and set up several fans to dry the bejesus out of all chambers.
Or just take off your fenders which is the best bet. Then blow out cowl and all you can get to.
You can get a shop vac and put the hose on the outlet to make a pretty good blower.
Vacuum all chambers you might possibly reach. I put a flexible 1" diameter clear vinyl hose on the end of my shop vac hose, with tape, then shoved it into all hard to reach chambers to remove any debris. Behind the door striker is a big chamber, around-above rear wheel well in trunk area, between trunk floor and rear quarter area is a gap where crap collects and in the front pillar where the bolts for door hinges bolt thru.
Leave vehicle open at night if possible, hood, doors, trunk. Let the air flow thru with fans. The more air blown thru all the areas, and the more clean all the little hidden chambers, the less chance of rotting debris and mouse urine smell.
I seriously hate having mice in a vehicle. The smell and idea of mice living, pooping and dying in my dash just sucks. !