Hitching the deadlift is a combination of supporting the bar on the thighs and rebending the knees to obtain a sequence of knee extensions to crawl the bar up the thighs in a series of steps. It is only acceptable in CrossFit because it is not a single pull and does not strengthen the movement the way a legal deadlift does. This is similar to their insistence on bouncing deadlifts off the floor. A good rule of thumb is: if CrossFitters do it and it deviates from the traditional technique, it's easier. Easier does not make you stronger. This is why no CrossFitters deadlift 750.
You are stalling at 355 because you are 6'2" and 215.