There are a lot of rodent runways built into these campers.
Start by pulling all the lower drawers out of every cupboard/cabinet you have. also open all the lower cupboard/cabinet doors. Now look for all the holes they cut thru the floor. Also outside on the frame, there is holes there to. Cover them with black duck tape. Inside, you can use either steel wool, or if you are concerned about it rusting, I think you can get a copper type wool instead. Plug the big holes in the floor with that and finish sealing with spray foam.
Outside where you mentioned, I don't have an answer for that. I don't know what it looks like.
2008 Cruiser CF26RK
2013 Ford Eco-Boost
Heavy duty payload - Max tow