I read all about the EB towing UP mountains, but never hear the owners of said trucks talk about how they handle and slow down on the steep grades! Let's HEAR what the owners have to say!
I've found that while towing, engine braking is almost nonexistent until it hits about 4000 RPM. For the bigger hills, I'd let the weight take it up to about 5000 RPM then apply the brakes to about 4000 again. Repeat as necessary.