Upping the R Value

I camped out last night in a Altaplex, using a 0 degree quilt and a 5.4 r value pad. I had a puffy on it only got down to 38 degrees in PA and I nearly froze. I’m Planning on starting a thru hike on the AT next March when it’s probably gonna get much colder. Other than dropping another $200 for a higher rated pad or adding too much to my pack weight. What do you folks do to raise the R value so you can get a good nights sleep. Thanks