I don't understand all of this, and I may be adding to the confusion by posting about my experience, but . . .
A couple of years ago, I lost my trailer brakes in Gunnison, CO just as I left the campground on the way to Colorado Springs (via Canyon City and CO 115). Anyway, I blew out all the fuses I had and on a Saturday morning could not find any help, so I decided to take it easy and go on with no trailer brakes. We had NO problems over Monarch Pass and on to Canyon City. In that town, a young woman in a small car pulled out in front of me just as we were approaching a traffic signal. She decided to stop quickly. I must admit, that was a close call but it was truly a "panic stop." With only that one incident to cause concern, we made it on to Cheyenne Mountain State Park with only the pickup brakes. We were able to get the trailer brakes functioning for the rest of a long trip up through the Dakotas.
My pickup is a 2008 Duramax/Allison 2500. The trailer a 32.5 UKTG HitchHiker II. (Actually 33' 10")
None of this is intended as a recommendation, but I think it does show that there is a good bit of margin of safety in an emergency. I hope this encourages the first time fifth-wheel driver. We have had four and have traveled over 150,000 miles.