While you are talking with Keystone, you might send an email to Marcus Lemonis, CEO of Camping World and Good Sam. He has "promised" to improve the operations and customer relations at Camping World and seems to be quite open to suggestions and experiences - good and bad - from CW customers.
His email address is:
[email protected]
I'd also send a copy to the dealer of your email as well as a note indicating that you will be in contact with Keystone to discuss the $800 fee and the "threat" to revoke your warranty if you refuse the PDI.
I hope you haven't yet paid the $800 to the dealer. I think it is important that you try to maintain a civil and a reasonable working relationship with the dealer --- they are the ones that you will probably need to go through to get any warranty work done and if you come on too strong, they could make it difficult for you down the road. Be polite but be firm.
Let us know how things progress with Keystone and the dealer. Good luck with this.