Coffee (me), Tea (wife) & Milo (kids) before bed. Sometimes something a bit stronger for the parents.
We have a soft floor and run shade cloth (enviromesh stuff) under the floor and if really cold we also slide the kitchen in and close the tailgate to stop the cold a bit. Good doona on the bed and 2 kids in black wolf -10degree sleeping bags & everyone has thermals. Cannot beat thermals and layers as opposed to big bulky items.
Should have a look at current Kathmandu Easter sale as 3 pieces of thermals (tops, bottoms etc) are $75 = $25 a piece. A good thermal top for the kids to wear underneath makes a big difference.
I dont run any heaters or anything in the tent - we just keep rugged up and wait for the sun to rise!
We are planning 4weeks around Alice Springs in July so this topic is quite relevant as I keep being told to be prepeard for cool nights. Might throw a couple of hot water bottles in!