New 5th wheel purchase. I think we have a lemon, need advice

I'm sorry you didn't find those things during the PDI. And if it were me and I somehow ended up with those issues. I would fix as many as I could myself. None of them seem to be anything more than fit and finish. And I would know that they were fixed right. My thoughts about RV ownership include fixing thing myself. Even under warranty. It makes the whole process of ownership more sustainable IMHO...