Depending on your state can be different different. Some states like NC say that if the repair is 75% or more of the "value" of the vehicle, they will total it. And value is fair market value. Insurance companies won't use NADA, they use sold comps and they are usually lower than you think.
Your Rv is 15 years old. My guess it will have structural, water, electrical etc etc. It doesn't help that labor is probably $120/hr. In short, my guess would be that they total it, and the value will be less than you think.
Jeff - 2023 FR Sunseeker 2400B MBS