Ill bet there getting in thru the baffles in the rear quarter panels
The vents are to allow air flow out of the vehicle when you're pulling in outside air, especially when the windows are closed, so you don't want to plug them. You may want to fabricate a screen cover to keep the rodents from coming in.Ahh, that makes sense. There was a lot of prints and poop in the very back corners, under those two little rear carpet panels.
Where abouts are the "baffles" and drainage holes? I imagine I'll have to stuff them with steel wool or something? I've never really had to deal mice before, so any suggestions are welcome.