Today I know very few people who are aware of the proper care and handling of "canvas" My son had a small old coleman but in good shape. He immediately believed he had to waterproof it, WRONG! Of course the fabric shrunk and never again fit the frame. It did remain usable and I inherited it.
Once when I was using it, I had a guest when it was raining. They reached up and touched a small sag and of course the water came through. I was only 5 yo when we first lived in a tent for several months while daddy built our first home. There were 3 of us kids and we learned not to ever touch the roof so that when it was wet, it would still shed water. There wasn't anything in any spray cans in "those days"! Some people did oil their canvas but they smelled and collected dirt. The main thing was to always have the canvas taut and no touch. A good wall tent on the ground with a smal heater, gas or wood, can be even nicer than any trailer in the serious cold. We once had 7 trailers in an elk hunting camp but the gathering for all each evening (for telling stories) was a small tent with a wood stove!
I have never known of anything colder than these pop-up slide out beds in cold weather. The tough lessons are not forgotten!