In short, I doubt that combo would be warm enough.
Richard Nisley's work has shown that "Survival-" rated pads for freezing have an R-value of around 3.5, Comfort around 6, Max Comfort around 9. See the following thread.
If I recall correctly, the 1/4" thinlight has an R-value of less than one; in conjunction with the 2.5 of the NeoAir, best-case scenario you'd have a pad with R 3.5, maybe.
I just got back from a trip using a NeoAir, most nights in the 40s, one or two nights into the 30s. I froze! Frankly, before I realized what was going on I found myself layered up with a baffled down jacket, two layers of wool, inside a warm 30* bag, and sweated profusely into my down gear... but still felt very cold the whole night. Hindsight being what it is, I realized that the pad was woefully inadequate for those temperatures (edit: for me). It was marginally comfortable for those nights in the high 40s. YMMV.
For trips where I expect the temps to drop to around freezing, I've historically used a pad or pad combo to achieve an R-value of around 6. When I bumped up to a Downmat with an R-value of 8, I was very pleasantly warm, even at zero.