Sadly, you need to clean the vents. Mice can carry diseases.
Your HVAC system is contaminated with urine and feces, and it may be home to a decaying carcass.
Cover your interior furniture with plastic.
Vacuum out the ducts...preferably with a long extension hose on the vac, and the vac unit outside the coach so that you don't redistribute rodent waste in vac exhaust. https://www.amazon.com/Cen-Tec-Syste...xpY2s9dHJ1ZQ==
You may then adapt dryer vent brushes to push swabs/rags with cleaning solution...clorox perhaps...through the ducts. Also check the AC units to see that they are clean. Don't saturate the rags...just dampen them.
My brother encountered this in his fiver, and it took a LOT of work to decontaminate.
Wear a mask and rubber gloves while doing this work.
If you happen to have any N-95s laying around, used those. If you don't use any mask. And cleanup the interior to deal with the inevitable debris that escapes the ducts.
This may seem like overkill, but read the disease link again.
Then get to work and figure out how they are getting in. Rodents' teeth hardness is just shy of steel. Foams, aluminum and other soft materials present no barrier. Sheet steel flashing and hardware cloth work.
I've had very good luck repelling rodents with Freshcab: https://www.walmart.com/ip/Fresh-Cab...BoCFHEQAvD_BwE
Use liberally. I have 8 of them in my 24' camper. In 10 years at my current home, I've never had a rodent in my rig.