Wish I could help more but it looks to me that those who said to put repellents out would be the best answer-- moth balls and dryer sheets and such. After that you might have to use something metal to cover the bottom of the trailer. Most animals that gnaw their way in won't gnaw on anything metal. I would try to drive them out before I sealed up the holes. Joraz sounds he has a handle on the problem.
I've only seen one pack rat. It is not really a rat. It has a furry tail with a white tuft at the end. It's ears are larger. It's body is larger.
The thing wasn't scared of us and tried to hang around the campfire.
It climbed up a tree when we finally scared it away.
Or was this something else? This was in a mountainous corner of Tn and Alabama.
Also have had good luck with lights. With our mid-engine cannot open the hood so we placed lights on the engine-the two Pack Rats did not return. PS-poisen did not work as they towed away a heavily wired rat trap.
2007 Newmar 42' Mid Engine w/Fatboy,Grizzly 550s-in Garage,Rubicon w/4" lift,MotorMetal whls,MickeyT Baja tires-Cherokee w/4"lift in tow, Hog Valley FL(a diamond in the rough) 2010 Part2