I agree with most of the advice, save turning up the brakes on the trailer. A sliding wheel will lead, because it has less friction than a rolling wheel. This is what the engineering textbooks say, but don't believe them or me.
Prove it to yourself like the Dowell Schlumberger driving school proved it to class after class of drivers. A model tractor-trailer with quality spinning wheels and a steep incline. Roll it down, then roll it down with the trailer wheels (toothpicks or erasers) locked, then repeat with the drivers locked. It violates your beliefs, but your camper will react the same way. The sliding wheels will lead. You want even braking, all the way around and don't lock up. We also drove cars on a skid pad, where the instructor could lock front, rear or both.
Then you can shake your head and give the truck to the kids as a quality toy.