I’m not sure military canvas is coated. Mine isn’t coated but I’ve been caught in the rain with it and it didn’t soak through. I too do not baby my bags!
I’ve currently just got a black and white twilly on this bag (forgotten the name of it). Usually I’m a very monochrome person so I decided not to get colourful twillys for this bag. My orange Herbag has a more tonal Twilly on it (oranges/browns).
My SA absolutely loved that I turned it inside out! I have also added a bag organiser to it from Samorga to help keep the shape better and keep it clean and easiest to find things!
Enjoy your new bag!
Monochrome twilly sounds like a great idea, I was thinking more bright orange or red tones. But I like your idea.
Now to find some!