Those passes you mentioned are steep with curves. Did Wolf in a workhorse towing a 4000lb jeep and it was slow up and down. At 20mph it was a long day to make that pass. This was my dads rv at the time. I had a 26' 2011 vista and it was lighter in weight and does grades a little better. Did the drive from silverton to durango with it and the only complaint was from the passenger chair. Vista had no problem towing my jeep on that stretch. As mentioned, the tow haul mode is awesome when going down steep grades and sometimes brakes are not even required. Even if you got a dp on the passes you mentioned with all those curves you are just not going to drive that fast. If you are not in a race you will have no problems. Can you do it without trailer brakes, sure. But since you are doing a lot of grades I would definitely look at getting them.
