If at all possible, avoid camping in the valley bottom. Cold air drainage is a simple physical fact while afternoon hillside updrafts might be common.
Get up the hillsides as best you can. The view is usually better, too.
Sunset. October. A thousand feet above the Fraser River can be 5C warmer than at my house in the village.
Put dry clothes/longjohns on to go to bed. In the morning remove dry wear and put your day clothes on, which may or may not be damp. Good tip in an earlier post about having warm feet in bed; makes a huge difference in getting to sleep. Also don't let yourselves get cold before getting in your sleeping bags.
It's a lot easier if you get all your admin/cooking/eating/clearing up/tidying away done while it's still light, rather than faffing around in the dark with a head torch.
A pee bottle is also a good thing to have in the tent at night. Saves losing body heat using the outside "convenience" during the night. A little bit awkward when sharing a tent with one's daughter I completely agree. There are female equivalents but this aspect of "comfort breaks" may not be appropriate in the shared circumstances of your planned trip.
My kit consists of an exped downmat 7 which is rated to -24c and a 2-3 season down sleeping bag plus liner. I'm always cosy with this and I camp at 600ft above sea level in Aberdeenshire. I have to agree with what other have said. Sleeping bag comfort ratings are about 5c out, or maybe I just sleep cold.
My mate came along camping with a supermarket inflatable mattress and almost got hypothermia. He had a very bad camping experience and has since bought a decent sleeping mat.
Alcohol is a vasodilator. Sure might be a wonderful taste sliding down but, your caloric body heat loss from subcutaneous blood increases.
I'll say that it's OK in spring/summer/autumn but not after a day chopping ice steps.