I used to work for a canvas tent maker in Oregon, we used some generic 10oz cotton duck but I got to see most all the major tent makers in the country come through for seasonal drying and repairs, we called down curses on all the companies using 24oz canvas as it was awful in every way.
I'm pretty sure the army used 7oz canvas in their smaller "half shelters" and I was very impressed with how wind and waterproof that material was, I'm sure its treated with all kinds of nasty stuff but it does work. I mostly cut them up for anoraks or wrapped up in them for cowboy camping.
My usual canvas lecture is that I saw 50's Hirsch Weiss (white stag) tents that looked like they came off the show room floor and I saw 6 month old tents you could put your finger through, maintenance is everything. Trying a 4-5 oz canvas tent is on my list, but I don't get much weather in my current home to give it a test.
I come down on the "don't worry too much" side of things for stoves and fabric, I've spent the last few years working with silnylon hot tents and even guys running stoves with no spark arresters can't manage to burn down their tents unless they manage to start a grass fire first. In the time I worked at the canvas shop I only heard of one tent burning down, and I didn't get too many of the details. Polyester is the only fabric that I would recommend against, nylon only melts, cotton usually chars but polyester burns like its going out of style. Even a lot of waxed canvas gets worn around campfires without anyone's coat going up in flames so I have a hard time being too worried about an oilskin tent, but testing is warranted. I also did some UV testing on some shelter fabrics and one of the discoveries was that the wax leaves the cotton pretty quickly when left outdoors long term so it would probably be moot after a few months anyway.