It's a sleep system, not a sleeping bag issue. You can put every stitch of clothing on to make up for higher temperature rated bag and be comfortable or have a zero rated bag and not be able get your feet warm.
A lot depends on the ground. If the ground has been frozen or is frozen, you may need to double pad. Once we near October, I will take Therm-a-Rest Z foam pad to supplement my 3 season Big Agnes Air Core along with a 15* F Marmot Pinnacle bag.
There is more than a few to skin this cat.
