Just as a FYI, I also have a Pinnacle on order. When I discussed the disc brake option, my dealer pushed me away from it. Their explanation was that since I'm on the East coast, I probably would not need them. You being located in the West with more challenging terrain, I can see the need. Have you tried contacting Jayco direct? I have found their support staff knowledgable and very responsive the few times I reached out. You may not be the first to ask that question of them.
Good luck.
PS, tried to PM you, but the system would not let me.
MC