I think the idea of boiling up a brew first thing in the morning inside the tent is the way to go. It not only puts heat into the tent while the water is boiling and the steam rising but having a lovely cup of tea warms you as well. It is just a qustion of getting a suitable set up.
Have a look at this http://www.myoutdoorstore.com.au/JETBOI ... 65127.aspx
as they are designed for use inside tents.
The danger of cooking inside tents(which I have done many times on expeditions) is from knocking the pot/stove over and either scalding yourself or setting the tent alight. The danger of carbon dioxide or monoxcide posioning from a small stove used just as directed in a tent is not even worth thinking about. It is, as always, a matter of being sensible.
If you have a setup like the one above where you emliminate the possibility of it being knocked over then you are sorted.
Feel free to contact me if you want any further advice.