What I find really helps is selecting the proper clothing to sleep in.
It will really extend your temp range.
Fresh heavy wool sock with down booties, heavy weight long underwear, micro fleece top, down jacket with hood, light balaclava, wool watch cap, wool gloves.
Set your tarp up to block the most wind.
My military weight polypro set has saved me on a few unexpected cold nights. Both in a hammock and tent. Not only does it keep your bag cleaner, some say, but when you get up in the morning you have a little protection from that holy crap moment when you first step out of your fluffy nest into The cold.!