Sorry about your squirrel problem.
It's almost impossible to seal up any RV so squirrels and mice can't get in. I have never known anyone personally who has conquered this quest successfully.
The best solution I've heard of was a friend who tried everything and couldn't keep rodents out of his rig where he stored it by his workshop. So he fenced it and kept a dog in there. No more rodents
Can't say that I would blame the factory, but that's just me.
Hopefully your rodent problem will lessen.
Scott and Liz - Southern NM
2012 Wildcat Sterling 32RL - w/level up (best option ever)
2007 Chevy 2500HD 4dr short bed Duramax w/allison
Reese Fifth Airborne air ride king pin coupler with Sidewinder