You will have to use a 2nd hotbar most likely. I have two for both Warrior and monk with all of my main offensive and defensive GCDs on the 1st hot bar with things like stance switching and very situational things on the 2nd hotbar. You can set it up to where if you hold L2 and hit R2, it goes to one of your second hotbars and viceversa which can help. You are right that there is pretty much no way to get everything onto 1 hot bar, though.