Hi Janine,
It's do-able in a day but just be prepared for it to be a monster one! I've no idea how you are with altitude but make sure you have food/drinks that that your body will allow you to consume at that height because you will be expending huge amounts of energy. For me, that's the one area I struggled on and would have had a much more enjoyable day if I could have eaten more.
Good luck and I hope you have a great time!
