I agree with Fiddleback. I have two total hangs with a pad under me ever. My first hang, overnight low of 39 degrees, Walmart CCF pad below me (pad unmodified) and a North Face Cat's Meow 20 degree bag. As most of you would guess, I was quite warm. I slept most of the night with the bag unzipped and my arms out of the bag, hood off. At one or two points, I slid off the pad, getting a cold butt and shoulder, where I woke up and readjusted. Also, at one point I got cold in general, so I zipped the bag up and tossed the hood on. Super cozy then.
The next night, overnight low was 46 degrees. I used a Mountain Hardware Ultralamina 32 degree bag with the same pad, but I modified it to make it wider for the shoulders. (Basically an SPE made by cutting the pad and using duct tape to hold the modification together.) I know I have overcompressed the life out of this bag too many times (before I knew it was bad to do that...) but nonetheless, I was pretty dang chilly. I blame it on the bag. Perfect example of how the system is important, not just the pad (or any other singular aspect of the system).
My recommendation to you is to go buy one of the Walmart CCF pads. I think mine was $7. Is it light? Nah. Mine weights like 15 oz. But it's a good way to figure out of pads are something you want to even bother fiddling with, or if you should just make the jump to an underquilt.
"Get busy living, or get busy dying."
Warbonnet Blackbird 1.0 DL
Warbonnet Edge Tarp
North Face Cat's Meow 20°
Custom HammockGear.com Phoenix Underquilt