Yes, as much fun as I've had making things from synthetic insulation. I would say that to get to 10F easily and not have to manage a ton of extra bulk, you'd want to get an overstuffed down quilt or two.
Otherwise, you'd layer a bunch of synthetic insulation(s) and then manage the bulk to temp ratings issues. Depends on how much you hike, and what your pack weight goals are, I suppose...
I'm about to start making an overstuffed down multi-quilt in these same colors, woodland camo and black. Now that enough people have made down quilts before me, I feel fairly comfortable following their posted directions and making my own. (What a great site!) Right now I'm saving my money to buy the down, which is way too expensive, but I think is ultimately the way to go...
"Civilization is the limitless multiplication of unnecessary necessities." - Mark Twain
“I go to nature to be soothed and healed, and to have my senses put in order.” - John Burroughs