+1 on wearing extra insulation to sleep. It extends the temp range of your bag or quilt, but the reason I do it is for when I wake up. It really makes the 'do I really need to go?" debates a lot less distressing.

You might reconsider the blanket idea because a liner will be smaller than your bag and might feel confining. Throwing a layer over the top works, but if you have a lot of room you can stuff the blanket in with you to fill air gaps.