It is worth getting someone in the know to help you adjust the harness, I losened mine a bit and from that point on couldn't reach my valves for shut downs. But Clare helped sort it back into it's correct position, having it to loose meant the backplate ends up to low. So now I can reach the valves again
Getting out of the one piece isn't as hard as you might imagine with a bit of practice, just remember to deflate the wing first and if possible drop your bum while the rig is supported, then left arm out bla bla... oh and remove the back up reg first.
Neil