I completed a three day solo trip last week just below the rim. My sleep system was similar to yours. So I think you are probably on the right track. Although, I used a lighter pad than you are using. But, I was backpacking over a fairly long route.
As suggested by another, I think the larger tarp would be wise if you expect rain.
The only other thing I would comment on is that you might want to pay close attention to the clothing you will be sleeping in. You should probably be wearing at least a good set of insulating underwear, stocking cap, and socks that you feel will help your feet stay warm. Add to that according to whether or not you tend to sleep cold or warm.