General question, tandem trailering and trash bag windows aside: Trailers over 3000 lb. require brakes in PA, and I suspect most states have similar limits. So how are these types of car haulers ever legal?
It appears most states require brakes on only one axle of the trailer, such that the towing dolly could be outfitted with brakes to make it legal. But in some states, including Pennsylvania, brakes are required on all axles of any trailer over 3000 lb. That doesn't seem possible with this type of rig.