Mice issues in RV underbelly

Thanks for the input. I talked to the campground owner who also services RV and he claims it's not worth tearing the galvanized underbelly to replace insulation - but that's just his opinion. He offers to borrow an ozone machine and run it for several days in the camper while the place is vacant. He also claims there is no wiring in the underbelly which I confirmed by calling the manufacturer, they actually gave me literally the same answer. Only trailer lights through underbelly, all 110V electric through walls and ceilings.

I am tempted to use a shop vac and vacuum what i can reach then seal everything tight. I am also tempted to cut an access door within a closet space to reach and monitor the underbelly for the future. The closet under the stairs could accommodate a 2 by 3 foot access door. Obviously I would have to seal the seam but I see value being able to monitor the inside in the future.