I'm sorry to hear of your lost RV, and truly hope no one was injured in the event that resulted in it being totaled.
I don't have my policy with me but paraphrasing My Policy defines replacement as: If within 5 model years of it manufacture date and is totaled, will replace with a brand new RV as closely equal in features as the RV. If after the 5 model years then I will be reimbursed the $$ value that I paid for my RV.
I learned the hard way when in 2007 our 2002 Beaver Santiam burnt to the ground. Our policy was similar to the above statement with the caveated statement "Or at our discretion we will pay current market value
". That statement relieved the Hartford of replacement costs and left us $50K short of paying off the bank.
Trust me that I now have a different provider and a clearly spelled out definition of replacement value. Also my premiums reflect the added protection.
In all fairness I should note that the issue wasn't really with Hartford, because they do have a true replacement policy available, but rather an agent who promised one thing but then sold something else at a lower price to make the sale.
Good Luck with your negotiations. I would suggest the it is always easier to go in low key and them the chance to do the right thing. You can always negotiate more rigidly if necessary.