Short answer- spend some money. :-)
I've found three key components to a quilt/tarpt system in cold temps: warm headgear, a bivy, and thoughtful ground insulation.
Headgear- After several years with quilts, I go heavy on this insulation. I personally use a Cocoon Hoody and a Cocoon balaclava in those temps. I'd go for a warm insulated balaclava and a thing fleece balaclava underneath. Might be conservative, but I've found this to be key in a quilt system.
The bivy is key. I move around when I sleep which gives drafts and if winds pick up, you lose even more heat. The bivy is a key part of staying warm and I almost always use one under about 50 deg. (more above treeline). However, if you have a larger tarp that pitches to the ground, pick a spot carefully, and don't thrash when you sleep like me, you'll probably be fine.
At 30 deg., I think a torsolite alone will be cold. I'd go for your long Thinlight, the pack, and a Torsolite at those temps.
I spent some pretty uncomfortable nights in the beginning when learning to push a light quilt to cooler temps. I think you may want to be wiser than I was and go warmer. You can always ditch items on your next trip.
One caveat- I tend to be a bit of a cold sleeper.
Have a great trip!