Two Bags?

[RGR]

Looking for some advice. I am doing a solo paddling trip at the end of the month in the BWCA. I have an enoDN, and have slept in it comfortably a dozen times this summer using a thin thermarest(which I didn't need) and a 20 degree kelty down bag used as a top quilt. The temps are an average low in the forties for the BW at the end of sept. My question is would i be ok with a thicker pad like my BA downfill and the 20 bag or should I add another bag? I have a 15 degree synthetic Marmot bag that I have thought about adding, using as a base layer, pad inside with the kelty as a top. Thoughts?

[Beast 71]

My cousin uses a 20F bag and a Therm-a-rest and he does quite well. Matter of fact he is soloing the end of the month unless, I can go too.