Squirrels in the rear cap and attic???

The rear cap is just installed over a flat back trailer, and is attached across the top of the rear wall roof joint. They might find a cutout into the rear wall, but I question a ability to get into the attic via that route. Chris

If true that is good news. Where would I call to find out?

I do not think there is a route from the rear cap to the attic.

You sealed the back cap. It's a wide gap all rhe way across the bottom. Stupid design.

Yes, I cought mice in mine years ago. Got rid of them and sealed with foam.

I have already removed and replaced the underbelly plugging all openings from inside the frame. I made gaskets where hyd shaft for slide go.
But up the rear... the rear cap is all open at the bottom. Can they climb up there and into the roof??

Yes. The first trip we took with our FW was to a campground near Yellowstone. One morning we were awakened to the loud chattering of a chipmunk IN OUR KITCHEN! Our dog went crazy! DH went outside and climbed under the rig, but didn't find where they were getting in. When we got back home, he went through and stuffed steel wool in some places, expanding insulating foam in others and placed wire screen on the other side of the wood vent grill under the fridge in the kitchen. Lots of trips later, no happenings. Fast forward to 2014 and we took our FW into the dealership to have solar and a satellite system installed. They found up front in the wiring harness area, enough dried mushrooms to fill a plastic grocery shopping bag!