I've spent a few nights just under 30* this Winter and honestly I've been surprised at how warm I've been. My set up is very similar to yours and I've intentionally slept in must athletic shorts just to see if I could... So far no problems. My only advice would be to sleep on your coat, with it under the pad and the sleeves around your shoulders. This seems to really help keep my shoulders insulated since they don't stay on the pad...
I think you'll be fine. I always take a fleece sleeping bag insert, but I have yet to use it.
"We're the Sultans of Swing."