68 is the ideal overall for anyone to sleep in, not too warm and cool enough to get peaceful sleep.
Cooler rooms provide easier breathing too.
I say maybe it is time to consider a big kid bed, twin bed with a rail. If she is throwing things out to get your attention, leave it on the floor.
Layer her at night with a tshirt, loose sweat type pants and a feetie jammie over top. She should be more then comfortable with those and not need anything else.
Keep socks on under the feetie jammies if you are really worried about her feet.
If she isn't bothered by it, don't you be. Your stress is seeping onto her and it becomes a power struggle.
Put her to bed after the bedtime ritual and walk away.
Keep a thermometer in her room to gauge what temp it is truly in her room.
Mine thermostat is at 65 during the day and at 68 at night and upstairs is colder if the temp is cold at night due to the slope in our roofline. At about 65 with jammies, blankets layered my kids sleep fine. I put both of mine in twin beds by about 2 anyway and at 4 and 7 they sleep better if it is around 67 degrees it seems. They are all snuggled under their covers though my seven year old daughter I have to cover her back up before I go to bed. She also will cover herself back up if she gets out of the covers.
Keep it down during the day, you don't need to waste your electric bill on heating during the day with the sun and them being more active either. Keeping it at 68 all winter will save you a lot of money.
Layer her, leave her be or put her in a big kid bed with a rail. Don't worry, if she is cold she will let you know! :)