You have more time driving semis than I do (since all of mine is in the Kenworth that I never had a trailer on it, and I got my CDL on YouTube). That’s the best comparison, having the giant drum brakes. This is about 30k lbs with the Rover, a small 7.2L engine with an exhaust brake (no jakes) and the 6-speed Allison (so not enough gears to really match the RPMs ideally. I don’t know if you ever drove the 18-wheelers in mountain country, but I’ll say that Iowa hills ain’t gonna do much like the 5-10% grades out here that go on for miles, and miles, and miles. Tennessee is close, but even then my experience with moving trucks is their brakes are similar to this with less total weight. This thing is heavy.
Summary is it’s amazing how quickly this thing can accelerate downhill, with the exhaust brake on and it in gear, if I don’t have the gear selected correctly. If I mess up by one gear, the braking requires to downshift to the proper gear can be enough to smell brakes from this thing. That’s just one application to get down around 10-15 MPH required for a downshift.
Jakes do better than the exhaust brake, and of course a properly sized engine (should be 10+L instead of this 7.2L) would help. A proper transmission with more gears would help. This 6-speed really doesn’t match the gears properly to speeds for all cases. I don’t think the technique you listed would result in success, unless you consider likely use of runaway ramps a success.
When you’re talking about a smaller, disc brake setup, in flatter country (which is basically everyplace except out here in the west) then yeah that works fine with your technique although my preference is still to use engine braking as much as possible, which is pretty successful.