in all honesty with hair that long i really dont see how it doesnt get tangled. just sleeping with it would cause tangles to some degree.
i think that the hair still tangled when you last washed is because although it basically just sat there and then you lifted and rinsed the hair moves, which is impossible to stop.
growig hair doesnt tangle because of something with the outer layer of the hair all going in the same direction...i think that although this processed hair doesnt have that layer that is the exact reason it does tnagle when swished about...
personally short ofchanging style i would do what you were doing to clean and just use a wide tooth comb to comb through shampoo and then just stand under the water to rinse..
its crazy to not be able to brush a hair system with the proper brush, i have never heard such a thing