Must be nice to have friends. I usually put mine on and off by myself. I just climb into the truck and stand up with it on my back. Having a trailer I can walk up on that is close to tailgate level helps. Being dumb also helps.
But, to help clear everything and make lift off easier, I would try putting one person inside and have them stand up with it on their back, provided they work out or are strong. Once it clears all the hangers, slide some 4x4s, or other sizes of wood, under the edges to keep it held up while you now position everyone around it to get it off the truck.